Portable field maintenance tool with bus for powering and communicating with field devices

Abstract

The portable field maintenance tool may perform one or more tasks, such as communicating with a field device, powering a field device, diagnosing a field device, or diagnosing a communication link connected to a field device in a plant environment. A portable field maintenance tool may interact with field devices configured according to a plurality of different communication protocols, such as a HART protocol and a Fieldbus protocol. The portable field maintenance tool may be energy limited and fault tolerant, and may operate in compliance with intrinsic safety standards, enabling use of the portable field maintenance tool in hazardous areas.

Description

[0001] This application is a divisional application of a patent application filed on July 21, 2017, with application number 202111560280.8 and name “Portable field maintenance tool having a bus for powering and communicating with field devices”. Technical Field

[0002] The present disclosure relates generally to portable field maintenance tools and, more particularly, to portable field maintenance tools that can be used in a variety of environments and situations. Background Art

[0003] Process control systems, such as those used in chemical and petroleum processes, typically include one or more process controllers communicatively coupled to at least one host computer or operator workstation and one or more field devices via analog, digital, or combined analog / digital communication links.

[0004] A process controller (sometimes referred to as a "controller"), typically located within a plant environment, receives signals indicative of process measurements (sometimes referred to as "control inputs") and uses the information carried by these signals to implement a control routine that causes the controller to generate control signals (sometimes referred to as "control outputs") based on the control inputs and the internal logic of the control routine. The controller sends the generated control signals over a bus or other communication link to control the operation of field devices. In some instances, the controller can communicate with field devices such as smart field devices (such as highway addressable remote transmitters). Wireless and Fieldbus (sometimes referred to as "Fieldbus") field devices) to coordinate the control routines implemented.

[0005] Field devices, which may be, for example, valves, valve positioners, switches, and transmitters (including, for example, temperature, pressure, level, and flow rate sensors), are located within a plant environment and typically perform physical or process control functions. For example, a valve may open or close in response to a control output received from a controller, or a measurement of a process parameter may be sent to a controller so that the controller can utilize the measurement as a control input. Smart field devices, such as those that conform to the Fieldbus protocol, may also perform control calculations, alarm functions, and other control functions that are typically implemented within a controller. Field devices may be configured to communicate with controllers and / or other field devices according to a variety of communication protocols. For example, a plant may include traditional analog 4-20mA field devices, Field device or Fieldbus field device.

[0006] Traditional analog 4-20mA field devices communicate with a controller via a two-wire communication link (sometimes called a "loop" or "current loop") configured to carry an analog 4-20mA DC signal indicating a measurement or control command. For example, a level transmitter can sense the tank level and send a current signal corresponding to the measurement via a loop (e.g., a 4mA signal for 0% full, a 12mA signal for 50% full, and a 20mA signal for 100% full). The controller receives the current signal, determines the tank level measurement based on the current signal, and takes some action based on the tank level measurement (e.g., opening or closing an inlet valve). There are generally two types of analog 4-20mA field devices: four-wire field devices and two-wire field devices. Four-wire field devices generally rely on a first set of wires (i.e., a loop) for communication and a second set of wires for power. Two-wire field devices rely on the loop for both communication and power. These two-wire field devices can be referred to as "loop-powered" field devices.

[0007] Process plants often implement traditional 4-20mA systems due to the simplicity and effectiveness of the design. Unfortunately, traditional 4-20mA current loops only send one process signal at a time. Therefore, a setup that includes a control valve and a flow transmitter on a pipeline that transports materials may require three separate current loops: one for carrying a 4-20mA signal indicating a control command to the valve (e.g., to move the valve to 60% open); a second for carrying a 4-20mA signal to the controller indicating the actual position of the valve (e.g., so the controller knows to what extent the valve has responded to the control command); and a third for carrying a 4-20mA signal to the controller indicating the measured flow rate (e.g., so the controller knows how changes in the valve position affect the flow rate). Therefore, a traditional 4-20mA setup in a plant with a large number of field devices may require extensive wiring, which can be expensive and lead to complexity in setting up and maintaining the communication system.

[0008] Recently, the process control industry has moved toward implementing digital communications within the process control environment. For example, The protocol uses loop DC amplitude to send and receive analog signals, and also superimposes an AC digital carrier signal on the DC signal to enable two-way field communications with smart field instruments. As another example, the Fieldbus protocol provides all-digital communications on a two-wire bus (sometimes referred to as a "trunk," "segment," or "Fieldbus segment"). The two-wire Fieldbus segment can be coupled to multiple field devices to provide power to the multiple field devices (via the DC voltage available on the segment) and to enable communications for the field devices (via AC digital communication signals superimposed on the DC power voltage).

[0009] These digital communication protocols generally enable more field devices to be connected to a particular communication link, support more and faster communications between field devices and controllers, and / or allow field devices to send more and different types of information to process controllers (e.g., information related to the status and configuration of the field devices themselves). In addition, these standard digital protocols enable field devices made by different manufacturers to be used together within the same process control network.

[0010] Regardless of the communication protocol utilized, field devices may require on-site setup, configuration, testing, and maintenance. For example, before a field device can be installed at a specific location in a process control plant, the field device may need to be programmed, and then may need to be tested before and after the field device is installed. For maintenance reasons, or for example when a fault is detected and the field device needs to be diagnosed for maintenance or repair, the installed field device may also need to be checked regularly. Generally speaking, the configuration and testing of field devices are performed locally using a handheld maintenance tool (e.g., a portable test device ("PTD")). Since many field devices are installed in remote, difficult-to-reach locations, it is more convenient for users to use a PTD rather than a full configuration and test device to test the device installed in such a remote location, where the full configuration and test device may be heavy, bulky, and non-portable, and the installed field device usually needs to be transported to the site of the diagnostic device.

[0011] When a user, such as a service technician, performs maintenance testing and / or communications with a field device, the PTD is typically communicatively connected to a communication link (e.g., a current loop or Fieldbus segment) or directly connected to the field device (e.g., via a communication terminal of the field device). The PTD initially attempts to communicate with the field device, for example, by sending and / or receiving digital communication signals along the loop or segment. If the current loop or segment is in the correct operating condition, the communication signals can be sent and / or received without any problems. However, if the loop, segment, or field device contains an electrical fault such as a short circuit or an open circuit, communication may be blocked and the loop, segment, and / or field device may need to be diagnosed to identify the fault.

[0012] When identifying such a fault, the technician may need to use various other tools to test the field device and / or the communication link. As an example, the technician may need to carry a multimeter to diagnose the actual signal sent or received by the field device. Since the traditional PTD cannot accurately analyze the electrical characteristics of the signal sent or received by the field device, the multimeter is necessary. As another example, the technician may need to use a portable power supply to power the isolated field device. The technician may need to power the isolated field device, for example, when the field device is powered off due to a plant-wide power outage or due to a problem with the local power supply. As another example, the technician may simply need to take the field device offline for troubleshooting in order to avoid negatively affecting other field devices and the rest of the process control system. The technician may also need to carry a multimeter to measure the current available on the segment or loop, etc. Each of these tools can take up considerable space and may be inconvenient for the technician to carry to the site. In order to solve the problem of carrying multiple tools, manufacturers have developed PTDs that include power supplies that provide power to the HART loop. Unfortunately, these powered PTDs are generally unable to provide power to Fieldbus field devices. Furthermore, typical portable power supplies and powered PTDs generally fail to comply with intrinsic safety (IS) standards and therefore cannot be safely used in hazardous areas (eg, potentially explosive environments or atmospheres due to explosive gases or dusts).

[0013] If the field equipment is located in a hazardous area, the technician may need to verify that each of his or her tools operates in an intrinsically safe manner. When in a hazardous area, the technician's tools may need to comply with IS standards to ensure safe operation. In general, IS standards require plant personnel to analyze all equipment attached to a loop or segment (including any PTD or other tools that will be attached to the loop or segment) to verify that all attached equipment will operate in a safe manner in a hazardous environment. More specifically, IS standards impose restrictions on electrical equipment and wiring in hazardous environments to ensure that the electrical equipment and wiring will not ignite an explosion. In order to comply with IS standards, electrical equipment generally needs to be designed with two core concepts in mind: energy limitation and fault tolerance.

[0014] The first IS concept states that IS equipment is designed so that the total amount of energy available in the equipment is below a threshold sufficient to ignite an explosive atmosphere. The energy can be electrical (e.g., in the form of a spark) or thermal (e.g., in the form of a hot surface). Although IS standards can be complex, they generally require that any voltage within a circuit be less than 29V, any current within a circuit be less than 300mA; and the power associated with any circuit or circuit component be less than 1.3W. Circuits with electrical characteristics that exceed these thresholds may pose a risk of explosion due to arcing or heat.

[0015] The second IS concept stipulates that IS equipment is designed in a fault-tolerant manner so that it maintains safe energy levels even after experiencing multiple faults. In short, IS standards reflect the idea that circuit failures are inevitable and that the energy level of the circuit must be limited to a safe level when these circuit failures occur.

[0016] Generally speaking, portable power supplies and powered PTDs are not IS compliant and therefore cannot be used in hazardous areas because: (i) the portable power supplies and powered PTDs are typically designed so that one or more components may exceed energy levels sufficient to present a risk of igniting an explosive atmosphere, and / or (ii) the portable power supplies and powered PTDs are susceptible to component failure that causes the portable power supply or powered PTD to exceed energy levels sufficient to present a risk of igniting an explosive atmosphere.

[0017] For example, a typical portable power supply may produce voltages (e.g., above 29V) at its terminals sufficient to pose a risk of explosion in a hazardous environment. Even when designed to provide voltages below 29V, a typical portable power supply does not include a fail-safe mechanism to ensure that the supplied voltage or current does not spike. Therefore, when in a hazardous environment, a technician who needs to provide power to a field device must typically uninstall the field device and transport the field device to a safe area where it can be powered and tested. Summary of the invention

[0018] The present disclosure describes portable field maintenance tools configured for use in industrial process control systems, environments, and / or plants, which are referred to herein interchangeably as "automation," "industrial control," "process control," or "process" systems, environments, and / or plants. Typically, such systems and plants provide control of one or more processes in a distributed manner that operate to manufacture, refine, transform, generate, or produce a physical material or product.

[0019] The described portable field maintenance tool can power field devices and / or communication links connected to field devices, communicate with these field devices and / or communication links connected to field devices, and / or diagnose these field devices and / or communication links connected to field devices. The portable field maintenance tool can be configured to be used with field devices configured according to multiple communication protocols such as Fieldbus protocol and HART protocol. Therefore, users are not forced to carry multiple tools for repairing different types of field devices, but only need to carry portable field maintenance tools. In some instances, the portable field maintenance tool can be energy-limited and fault-tolerant enough to meet IS standards. Therefore, unlike many prior art portable power supplies and PTDs, the portable field maintenance tool can be safely used in hazardous areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] According to an embodiment, each of the figures described below depicts one or more aspects of the disclosed system(s) and / or method(s). Whenever possible, the detailed description refers to reference numerals included in the following figures.

[0021] Figure 1A An example portable field maintenance tool coupled to a field device is depicted.

[0022] Figure 1B is a block diagram of an example process control system in which Figure 1A The illustrated portable field maintenance tool communicates with, diagnoses, or provides power to one or more field devices.

[0023] 2 is a schematic diagram of a prior art passive PTD communicatively coupled to a HART field device.

[0024] 3 is a schematic diagram of a prior art passive PTD communicatively connected to a Fieldbus field device.

[0025] Figure 4 yes Figure 1A A block diagram of a portable field maintenance tool is shown, depicting an example in which the portable field maintenance tool includes an active communicator for powering and communicating with a field device.

[0026] Figure 5A Yes, you can Figure 1A A block diagram of an active communicator configured for digital frequency modulation communications found in a portable field maintenance tool is shown.

[0027] Figure 5B Yes, you can Figure 1A A block diagram of an active communicator configured for digital amplitude modulation communications found in a portable field maintenance tool is shown.

[0028] Figure 5C Yes, you can Figure 1A A block diagram of an active communicator configured for analog communications found in a portable field maintenance tool is shown.

[0029] Figure 6 is a schematic diagram of an active communicator that may be found in an example portable field maintenance tool and that may enable communications via a digital frequency modulation communications protocol (eg, the HART protocol).

[0030] Figure 7 yes Figure 6 Schematic diagram of the resistor network shown.

[0031] Fig. 8A is connected to the transmitter Figure 6 A schematic diagram of a portable field maintenance tool is shown, which depicts an example of a transmitter being powered by an active communicator of the portable field maintenance tool.

[0032] Figure 8B is connected to the actuator Figure 6 A schematic diagram of a portable field maintenance tool is shown, depicting an example of powering an actuator by an active communicator of the portable field maintenance tool.

[0033] Fig.9A is connected to the transmitter Figure 6 A schematic diagram of a portable field maintenance tool is shown, depicting an example in which the transmitter is not powered by the active communicator of the portable field maintenance tool.

[0034] Fig. 9B is connected to the actuator Figure 6 A schematic diagram of a portable field maintenance tool is shown, depicting an example in which the actuator is not powered by an active communicator of the portable field maintenance tool.

[0035] Fig.10 is connected to the field device Figure 6 A schematic diagram of a portable field maintenance tool is shown, which depicts an example in which a power monitor of the portable field maintenance tool can be connected in parallel with a field device to measure electrical characteristics of a signal transmitted or received by the field device.

[0036] Fig.11 is connected to the field device Figure 6 A schematic diagram of a portable field maintenance tool is shown, which depicts an example in which a power monitor of the portable field maintenance tool can be connected in series with a field device to measure electrical characteristics of a signal transmitted or received by the field device.

[0037] Fig.12 is connected to the I / O device Figure 6 A schematic diagram of a portable field maintenance tool is shown, which illustrates an example of an I / O device that can be tested by the portable field maintenance tool.

[0038] Fig.13 is a schematic diagram of an active communicator that may be found in an example portable field maintenance tool and that may enable communications via a digital amplitude modulation communication protocol (eg, a Fieldbus protocol).

[0039] Fig.14A yes Fig.13A schematic diagram of a portable field maintenance tool is shown, illustrating examples of field devices to which the portable field maintenance tool may be connected that are connected to an operational bus.

[0040] Fig. 14B yes Fig.13 Schematic diagram of a portable field maintenance tool is shown, which illustrates an example in which the portable field maintenance tool can power and communicate with field devices via an internal bus of the portable field maintenance tool.

[0041] Fig.15 See through from outside of portable field maintenance tool Figure 1A A view of a communication interface of a portable field maintenance tool is shown. DETAILED DESCRIPTION

[0042] This disclosure describes a portable field maintenance tool and various techniques for implementing the portable field maintenance tool. Figure 1A An example portable field maintenance tool 100 ("tool 100") that can be connected to a field device 160 via a communication link 150 is depicted. Advantageously, the tool 100 is capable of not only communicating with the field device 160, but also powering the field device 160. The tool 100 can utilize a single composite signal transmitted via the link 150 for powering and communicating with the field device 160. In some cases, the tool 100 can diagnose problems with the field device 160 or problems with the communication link (e.g., a HART loop or a fieldbus segment; not shown) to which the field device 160 is connected in a factory environment. In some instances, the tool 100 can communicate with or diagnose field devices configured according to different protocols. For example, the tool 100 is capable of communicating with, powering, and diagnosing traditional 4-20 field devices, HART field devices, and Fieldbus field devices. Unlike many prior art PTDs that force the user to utilize multiple devices and / or force the user to connect multiple cables and wires to various different terminal sets if he or she wants to communicate with a field device, power the field device, and perform diagnostics on signals sent or received by the field device, tool 100 can use a single terminal set for communication, power, and diagnostics, and simplify the configuration and use of tool 100 for the user.

[0043] In addition, the tool 100 can be energy-limited and fault-tolerant enough to comply with IS standards. For example, the tool 100 can be designed so that all components of the tool 100 and all signals (e.g., including power and / or communication signals) sent and / or received by the tool 100 are energy-limited to a range that complies with IS standards. In addition, the tool 100 can "self-monitor" the components of the tool 100 and / or the signals sent or received by the tool 100 to ensure that the components and / or signals remain in compliance with IS. For example, when a component or signal approaches or exceeds a threshold associated with an IS standard, the tool 100 can disable one or more components (or completely disable the tool 100). Therefore, when the tool 100 complies with IS, the user can connect the tool 100 to the field device 160 or the link to which the field device 160 is connected (e.g., a HART loop or a Fieldbus segment), with confidence that he or she will not violate IS standards, and with confidence that he or she will not ignite an explosive atmosphere. In short, unlike many traditional portable power supplies and PTDs, the tool 100 can be safely used in hazardous areas.

[0044] The communication link 150 can be a two-wire communication link capable of carrying a communication signal and / or a power signal, each of which can be a part of a composite signal. As used herein, the term "signal" can refer to a communication signal, a power signal, or a composite signal that conveys both power and information. In general, the term "communication signal" refers to any signal that conveys information (e.g., a control signal that commands an actuator to actuate), and can be analog or digital and AC or DC. The term "power signal" refers to any electrical energy sent for the purpose of supplying power, and can be AC ​​or DC. The tool 100 can have a terminal set for connecting to the link 150 and the field device 160, and in some cases can have a plurality of terminal sets for connecting to field devices configured as various different protocols (e.g., a terminal set for a HART field device and a terminal set for a Fieldbus field device).

[0045] To power the field device 160 , the tool 100 may include a power supply configured to supply a voltage across terminals of the tool 100 to which the communication link 150 is connected.

[0046] The tool 100 can be configured to communicate with the field device 160 via a composite signal (sent via the link 150) that includes a communication signal (to facilitate communication between the tool 100 and the field device 160) and a power signal (to provide power to the field device 160). The communication signal can be a digital signal, an analog signal, or a composite analog and digital signal. In other words, the tool 100 can send and / or receive a first composite signal that includes a power signal and a second composite signal that includes an analog and digital signal.

[0047] For example, the tool 100 may include a first terminal set for sending and / or receiving a first composite signal (e.g., a HART signal) comprising: (i) a DC power signal (e.g., 4 mA) and (ii) a second composite signal for communication superimposed on the 4 mA power signal (e.g., an AC digital communication signal superimposed on the 0-16 mA DC communication signal). In such an example, the power signal is typically held constant at 4 mA and represents a live zero, resulting in the first composite signal having a current amplitude range of 4-20 mA. The tool 100 may additionally or alternatively have a second terminal set for sending and / or receiving composite signals according to other protocols such as the Fieldbus protocol. For example, the tool 100 may send and / or receive a composite signal comprising: (i) a DC power signal (e.g., 10-25 mA), and (ii) an AC digital communication signal superimposed on the DC power signal (e.g., modulated at 15-20 mA peak-to-peak). In some cases, tool 100 includes one or more terminal sets for sending analog and / or digital communication signals without providing power (eg, for situations where the field device is already powered).

[0048] As described above, the tool 100 can be operated in compliance with IS standards. That is, the tool 100 can be safely used in hazardous areas because the components of the tool 100 can be energy-limited and fault-tolerant in accordance with IS standards. For example, the components of the tool 100 can be (i) current limited to a current limit (e.g., 250mA, 300mA, 350mA, etc.) (ii) voltage limited to a voltage limit (e.g., 25V, 29V, 35V, etc.) and (iii) power limited to a power limit (e.g., 1W, 1.3W, 1.5W, etc.). The tool 100 can have one or more built-in redundancies (e.g., automatic shutdown, redundant components, etc.) to ensure that component failures do not cause these energy limits to be exceeded.

[0049] The tool 100 may include one or more of the following: a display 122, a housing 128, input keys 132, and a folding stand 152. The housing 128 may be shaped and sized as a handheld unit. The housing 128 may have a generally rectangular cube shape, or any other desired shape or size (e.g., 5 inches, 7 inches, or 11 inches measured diagonally).

[0050] The display 122 and input keys 132 may be disposed on the front face of the housing. The display 122 may be a touch screen, for example, a capacitive touch screen that detects touch input via capacitive sensing, or a resistive touch screen that detects touch input via applied pressure. The input keys 32 may be physical keys such as buttons or multi-directional buttons. In some cases, the tool 100 does not include the input keys 32.

[0051] The folding stand 152 can be pivoted between a flat position against the back of the housing 128 and a position pivoted outward from the back of the housing 128. In the flat position, a user can carry the tool 100 and use the tool 100 in a similar manner as a person uses a tablet computer. In the outwardly pivoted position, the folding stand 152 can be used to support the maintenance tool 100 in an upright position. In some examples, the tool 100 does not include the folding stand 152.

[0052] Figure 1B 1 is a block diagram of an example process control system 10 in which a tool 100 may be used to communicate with, diagnose, or power one or more field devices. The process control system 10 includes a process controller 11 connected to a data historian 12 and one or more host workstations or computers 13 (which may be any type of personal computer, workstation, etc.), wherein each host workstation or computer 13 has a display screen 14. The process control system 10 may include a plurality of field devices 160, including field devices 15-22.

[0053] Controller 11 may be connected to field devices 15-22 via input / output ("I / O") cards 26 and 28. Data historian 12 may be any desired type of data collection unit having any desired type of memory and any desired or known software, hardware, or firmware for storing data. Figure 1B , the controller 11 is communicatively connected to the field devices 15 - 22 .

[0054] Typically, the field devices 15-22 can be any type of device, such as sensors, valves, transmitters, positioners, etc., and the I / O cards 26 and 28 can be any type of I / O devices that conform to any desired communication or controller protocol. For example, the field devices 15-22 and / or the I / O cards 26 and 28 can be configured according to the HART protocol or the Fieldbus protocol. The controller 11 includes a processor 23, which implements or monitors one or more process control routines 30 (or any modules, blocks or subroutines thereof) stored in the memory 24. In general, the controller 11 communicates with the devices 15-22, the host computer 13, and the data historian 12 to control the process in any desired manner. In addition, the controller 11 implements a control strategy or scheme using one or more function blocks 32-38, wherein each function block is an object or other part (e.g., a subroutine) of the overall control routine 30. The function blocks 32-38 can be stored in the controller 11 or other devices such as smart field devices, and the function blocks 32-38 are executed by them.

[0055] The tool 100 can be communicatively connected to a communication link (e.g., a HART loop or Fieldbus segment) that connects one of the field devices 15-22 to the I / O cards 26 and 28 via a link 150. Alternatively, the tool 100 can be directly communicatively connected to one of the field devices 15-22 (e.g., via a communication terminal present on the field device 15-22). If desired, the tool 100 can provide power to the field device 15-22 to which the tool 100 is connected or to the bus (e.g., a Fieldbus segment) to which the field device 15-22 is connected. The tool 100 can enable a user to communicate with any one of the field devices 15-22 and / or to diagnose any one of the field devices 15-22. In some instances, the tool 100 only powers a single field device in the field devices 15-22 at any given time.

[0056] FIG. 2 is a schematic diagram of a prior art PTD 205 that is connected to a HART field device 215 via a HART loop 200A and requires the use of a portable power source 220. Unlike tool 100, PTD 205 cannot supply power to field device 215 and is therefore inconvenient for a technician. In addition, portable power source 220 may not comply with IS standards, making it unsuitable for use in hazardous areas. Finally, unlike tool 100, PTD 205 requires a loop resistor 210, connected in parallel with PTD 205 to loop 200A, to communicate with field device 215.

[0057] As described above, the PTD 205 does not supply power to the field device 215. Instead, the field device 215 is powered by the portable power supply 220. FIG. 2 shows a scenario where the field device 215 is being bench tested or the field device 215 is isolated from the normal power supply of the field device in the field. Because the PTD 205 does not supply power to the field device 215, when servicing the field device in the field, the technician may need to carry the portable power supply 220 for the field device in addition to the PTD 205.

[0058] As further described above, the power supply 220 may not comply with IS standards. Therefore, if the field device 215 is in a hazardous area, the technician may not be able to supply power to the field device 215, and therefore may not be able to use the PTD 205 to repair the field device 215. Typical portable power supplies are generally not safe for use in hazardous areas because they generally do not comply with IS standards. In particular, typical portable power supplies are generally susceptible to component failures, which may result in voltage, current, and / or temperature spikes sufficient to ignite an explosive atmosphere. It should be noted that if the PTD 205 is made "active" by adding a power supply, it will encounter many of the same problems encountered with portable power supplies that are related to IS standards.

[0059] Finally, like many prior art PTDs, the PTD 205 requires an external 250 ohm loop resistor 210 to communicate with the HART field device 215. In contrast, the tool 100 may include an internal resistor network that provides sufficient resistance to read a signal on a link such as loop 200A, and thus does not require the use of an external resistor 210. The external resistor 210 provides sufficient loop resistance to enable the PTD 205 to detect a voltage on the loop 200A, which is necessary to read the signal carried by the loop 200A (i.e., the PTD 205 interprets the detected voltage as a signal value). In this example, the PTD 205 can interpret an analog value (e.g., a tank level measurement between 0% full and 100% full) based on a specific value of the detected voltage within the range of 1V-5V (e.g., where 1V=0%, 5V=100%). For example, when the loop current is 20mA, PTD 205 detects 5V (i.e., 20mA*250), and when the loop current is 4mA, PTD detects 1V (i.e., 4mA*250). In addition, PTD 205 can interpret the digital component of the HART signal based on the detected voltage. The digital component of the HART signal usually varies about 1mA peak-to-peak. Therefore, the 250 ohm resistor 210 enables PTD 205 to detect a voltage of about 250mV (1mA*250) corresponding to the digital component. If a smaller resistor (or no resistor) is used, the voltage associated with the signal transmission on loop 200A may drop to a level that cannot be detected by a passive PTD. In contrast, tool 100 can utilize an internal resistor network with a resistance of less than 250 ohms, enabling tool 100 to read the signal on HART loop 200a while complying with IS energy restrictions.

[0060] 3 is a schematic diagram of a prior art PTD 305 that is communicatively connected to a Fieldbus field device 310 that is powered by a Fieldbus power supply 315 via a Fieldbus segment 300. PTD 305 is similar to PTD 205 in that it does not supply power to field device 310 and is therefore inconvenient for a technician. That is, when a technician is servicing field device 310, he or she typically relies on power supply 315 or a portable power supply (not shown) to power field device 315. In contrast, tool 100 can supply power to a field device (e.g., field device 310) even if field device 310 is located in a hazardous area.

[0061] Figure 4is a block diagram of a tool 100 depicting an example in which the tool 100 includes an active communicator 404 and a physical communication interface 406 electrically connected to the active communicator 404 via electrical connections 416 and 417, such that the active communicator 404 can power and communicate with the field device 160 via the physical communication interface 406, and measure one or more electrical characteristics of a signal sent or received by the active communicator 404. As shown, the communication interface 406 can be disposed through the housing 128, such that an external portion of the interface 406 is accessible outside the housing 128, thereby enabling the communication link 150 and the field device 160 to be connected to the interface 406.

[0062] The active communicator 404 enables the tool 100 to communicate with the field device 160, diagnose the field device 160, power the field device 160, and / or diagnose a communication link (not shown) in the plant environment to which the field device 160 is connected. In some cases, the active communicator 404 can be configured to communicate with and diagnose multiple different types of field devices (e.g., HART field devices and Fieldbus field devices), and / or can be configured to comply with IS standards so that it can be used to communicate with, diagnose, and power field devices located in hazardous areas. One or more power supplies of the active communicator 404 can include a switch for disabling the power supply.

[0063] The active communicator 404 may include a power supply for supplying power to the field device 160, a signal encoder and decoder (e.g., a modem) for communicating with the field device 160, and / or energy measurement circuitry (e.g., a voltmeter and / or an ammeter) for measuring electrical characteristics of signals sent and received by the active communicator 404. The active communicator 404 may send or receive communication signals to or from the field device 160 via electrical connections 416 and 417. The active communicator 404 may encode the communication signals by modulating the current amplitude or frequency to represent an analog or digital value, and may superimpose the communication signals on the power signal to create a composite signal.

[0064] The tool 100 may include a control unit 402 communicatively coupled to an active communicator 404 via a communication bus 414, the control unit 402 being configured to control and monitor the active communicator 404. At a high level, the control unit 402 may activate and deactivate components of the active communicator 404 to: (i) configure the active communicator 404 so that it remains energy limited in accordance with IS standards; (ii) configure the active communicator 404 to communicate in accordance with a desired communication protocol (e.g., HART or Fieldbus); (iii) configure the active communicator 404 in response to a connection made at the physical communication interface 406 (e.g., based on whether a user connects the communication link 150 to a terminal set for HART or a terminal set for Fieldbus); and / or (iv) configure the active communicator 404 for a particular field device configuration or field device type (e.g., actuator or transmitter). Generally speaking, a transmitter is a field device configured to obtain and transmit measurements (e.g., via a temperature sensor, pressure sensor, flow sensor, level sensor, etc.) The field device configuration or type may be determined based on user input or based on communication with a connected field device.

[0065] The control unit 402 may include a processor 422, a memory 424 storing one or more routines, and an I / O interface 426 communicatively coupled to other components of the tool 100 via the bus 414. The routines stored at the memory 424 may include a circuit manager routine 462 for activating and deactivating components of the active communicator 404 as described above and a diagnostic manager routine 464 for diagnosing signals sent and received by the active communicator 404.

[0066] The tool 100 may also include a user interface ("UI") 410 communicatively coupled to the control unit 402 via the bus 414, the UI 410 for providing a user interface and / or for detecting user input (e.g., touch input) received at the UI 410. The control unit 402 may provide the user interface at the UI 410 and detect user input at the UI 410 by executing a UI manager 466 stored at the memory 424. The UI 410 may include: Figure 1A The display 122 is shown, wherein the control unit 402 can provide visual output; and an audio device 444 for providing audio output. For example, the UI 410 can provide a graphical user interface that enables a user to select a communication protocol for communicating with the field device 160, to select commands to be sent to the field device 160, to view information sent from the field device 160 to the tool 100, etc. For example, the audio device 444 can generate an audio alarm or notification in response to an alarm sent by the field device 160.

[0067] In addition, the tool 100 may include a power monitor 408 (e.g., an ammeter) communicatively coupled to the control unit 402 via the bus 414, the power monitor 408 for measuring the current or voltage associated with the communication link 150 connected to the interface 406. The diagnostic manager 464 of the control unit 402 can utilize the power monitor 408 to measure the signal sent and / or received by the tool 100 to determine whether the signal has electrical characteristics within the expected range for a particular protocol. For example, if a user utilizes the tool 100 to attempt to command a HART valve to open to 50%, the power monitor 408 can be used to verify that the signal sent has a current (e.g., 12 mA) at or near a level that enables the HART valve to correctly interpret the signal. The UI manager 464 can display the measurement results obtained by the power monitor 408. In some cases, the tool 100 does not include the power monitor 408. However, regardless of whether the tool 100 includes the power monitor 408, the tool 100 can rely on the electrical measurements obtained by the active communicator 404.

[0068] The tool 100 may also include a wireless communication interface 412 communicatively coupled to the control unit 402 via the bus 414, the wireless communication interface 412 being used to send and / or receive wireless signals to enable the tool 100 to communicate with other components of the plant 10. The wireless interface 412 may support one or more appropriate wireless protocols, such as Wi-Fi (e.g., 802.11 protocol), Bluetooth (e.g., 2.4 to 2.485 GHz), near field communication (e.g., 13.56 MHz), high frequency systems (e.g., 900 MHz, 2.4 GHz, and 5.6 GHz communication systems), etc. In some cases, the tool 100 does not include a wireless communication interface 412.

[0069] Figures 5A-5C is a block diagram of active communicators 501, 511 and 521, each of which is Figure 4 4, and 512. In the example of active communicators 404 shown, these active communicators are configured to communicate according to different communication schemes. According to an embodiment, each of the active communicators 501, 511, and 512 can be communicatively coupled to the control unit 402 via the bus 414, and can be communicated via the control unit 402. Figure 4 Electrical connections 416 and 417 are shown electrically connected to the communication interface 406 .

[0070] Figure 5AThe active communicator 501 shown is a digital frequency modulation ("FM") circuit and may include a power supply 502 and an FM modem 504, each of which may be electrically connected directly or indirectly to the electrical connections 416 and 417. The power supply 502 may supply power to the field device 160 connected to the interface 406 via a DC signal. The FM modem 504 may use a frequency modulation scheme such as the HART protocol (via the interface 406) to send information to and / or receive information from the field device 160. For example, to send information, the FM modem 504 may superimpose an AC communication signal on a DC signal provided by the power supply 502. The FM modem 504 may encode a digital communication signal by modulating the frequency of the AC communication signal, wherein a first frequency (or frequency range) represents a digital 0 and a second frequency (or frequency range) represents a digital 1. For example, the FM modem 504 may encode a communication signal by modulating the frequency of the communication signal at 1200 Hz (representing a digital 1) and 2200 Hz (representing a digital 0). To receive information, FM modem 504 may interpret a first frequency or frequency range as a digital zero and may interpret a second frequency or frequency range as a digital one.

[0071] Figure 5BThe active communicator 511 shown in FIG. 4 is a digital amplitude modulation (“AM”) circuit and may include a power supply 512 and an AM modem 514, each of which may be electrically connected directly or indirectly to the electrical connections 416 and 417. The power supply 512 may supply power to the field device 160 connected to the interface 406 via a DC signal. The AM modem 514 may send information to and / or receive information from the field device 160 using an amplitude modulation scheme such as a fieldbus protocol. For example, to send information, the AM modem 511 may superimpose an AC communication signal on a DC signal provided by the power supply 512. The AM modem 511 may encode a digital communication signal by modulating the amplitude of the AC communication signal, wherein a first amplitude (or amplitude range) represents a digital 0 and a second amplitude (or amplitude range) represents a digital 1. For example, the first range may be 7.5 mA to 10 mA and the second range may be -7.5 mA to -10 mA. In some cases, a transition from a first amplitude or amplitude range to a second amplitude or amplitude range can represent a digital 0, and a transition from the second amplitude to the first amplitude can represent a digital 1. Thus, the AM modem 514 can control the current amplitude of the communication signal to cause a transition between the first range and the second range, thereby encoding a digital 1 (multiple digital 1s) and a digital 0 (multiple digital 0s) onto the communication signal. To receive information, the AM modem 514 can interpret a transition between a first amplitude, amplitude range, and / or amplitude (e.g., from high to low) as a digital 0, and can interpret a transition between a second amplitude, amplitude range, and / or amplitude (e.g., from low to high) as a digital 1.

[0072] Steering Figure 5C, the active communicator 521 is an analog circuit and may include a power supply 522, a DC current controller or current sink 524, and / or a DC current monitor 526, each of which may be electrically connected directly or indirectly to the electrical connections 416 and 417. The active communicator 521 may encode information by causing the current controller 524 to draw current at a specific magnitude within a certain range (e.g., 4-20 mA). Example information encoded by the active communicator 521 includes a command to open a valve to 100% open (e.g., 20 mA) or to 0% open (e.g., 4 mA). The field device 160 receiving the encoded signal may be configured to receive the signal and interpret the current amplitude as a specific command or a specific value. The active communicator 521 may additionally or alternatively decode the signal from the field device 160 by measuring the current amplitude of the received signal via the current monitor 526. Example information encoded by the field device 160 (to be decoded by the active communicator 521 and / or the control unit 402) includes flow measurements (eg, where the field device 160 is calibrated by sending a corresponding 4-20 mA signal to report measurements in the range of 0-100 gallons per minute).

[0073] In some cases, the tool 100 may include only one of the active communicators 501, 511, and 521; while in other cases, the tool 100 may include two or more of the active communicators 501, 511, and 521. When the tool 100 includes multiple of the active communicators 501, 511, and 521, the tool 100 may be able to communicate with and / or diagnose multiple field devices (e.g., HART field devices and Fieldbus field devices) operating according to different protocols. Advantageously, a user can carry a single tool in a factory to test multiple types of field devices, saving the user the trouble of carrying a different tool for each different type of field device.

[0074] When the tool 100 includes multiple of the multiple active communicators 501, 511, and 521, the interface 406 may include a terminal set for each of the active communicators 501, 511, and 521. In some instances, the active communicators 501 and 521 may share a power source and / or terminal set. In such instances, the active communicators 501 and 521 may carry information using a single composite signal modulated in both current amplitude and frequency. For example, the active communicator 521 may send and / or receive information by changing or measuring the amplitude of a DC signal between 4-20 mA. The active communicator 501 may then superimpose an AC communication signal (e.g., 1 mA peak-to-peak) onto the modulated DC signal.

[0075] Figure 6 is an active communicator 600 for tool 100 (which may be Figure 4 404) schematic diagram of an example of an active communicator 600 shown in FIG. Figure 1A The field device 160 shown is operated as follows: (i) power is supplied to the field device 160 via a DC signal (e.g., 4 mA); (ii) communicates with the field device 160 via a current modulated signal (e.g., 4-20 mA) biased on top of the DC power signal; and (iii) communicates with the field device 160 via a digital FM signal superimposed on the analog current modulated signal. Advantageously, the active communicator 600 can be used to communicate with and / or diagnose HART field devices. In some cases, the active communicator 600 can be energy-limited and fault-tolerant according to the IS standard, and enables the active communicator 600 and the tool 100 to power, communicate with and / or diagnose field devices and communication links located in hazardous areas.

[0076] As described above, the active communicator 600 can communicate with the field device 160 using two synchronous communication channels: a current modulated analog signal and a frequency modulated digital signal superimposed on the analog signal. Generally speaking, when the field device 160 is a transmitter, the analog signal conveys the original measurement value (e.g., flow, pressure, temperature, etc.), and when the field device 160 is an actuator, the analog signal conveys a command (e.g., open or close a valve). The digital signal can contain information from the field device 160, including device status, diagnostics, additional measured or calculated values, etc.

[0077] The active communicator 600 may include one or more of a power source 602, a resistor 604, and a communication circuit 609, each of which may be communicatively coupled to the control unit 402 via a communication bus (not shown). The communication circuit 609 may include energy measurement circuits (e.g., voltage monitors 611 and 616) that measure electrical characteristics of signals sent and / or received by the tool 100. The diagnostic manager 662 may analyze the electrical characteristics to verify that the signal is within an expected range for a given protocol (e.g., 4-20, HART, Fieldbus, etc.) or IS standard. The power source 602 may provide a power signal provided by the active communicator 600, and the communication circuit 609 may encode and decode communication signals sent and / or received by the active communicator 600.

[0078] A power supply 602, which can be designed to provide any desired voltage (e.g., any value between 20V and 29V), can be communicatively coupled to the control unit 402. In some cases, the power supply 602 can be designed not to exceed: (i) a maximum voltage threshold (e.g., any desired value between 23V and 30V), or (ii) a maximum current threshold (e.g., any desired value between 20mA and 35mA). In some cases, the power supply 602 can be designed to be voltage limited and / or current limited even when experiencing one or more faults, and / or can be designed to perform a changed startup or soft start during a period of time when the power supply changes to the desired voltage, thereby mitigating the chance of current spikes. In some instances, the current and / or voltage of the power signal provided by the power supply 602 can be measured so that the control unit 402 can shut down the power supply 602 when the measured voltage or current exceeds the maximum threshold or does not exceed the minimum threshold. A measured voltage exceeding the maximum threshold may indicate that someone has added an external power source to a field device connected to the tool 100, which may cause the loop to violate IS standards and / or may damage components of the tool 100 or other components connected to the loop. A measured voltage that does not exceed the minimum threshold may indicate that the circuit has been shorted, or that the capacity of the power source 602 has been exceeded. A measured current that exceeds the maximum threshold may indicate that the circuit has been shorted or that the power source 602 is limited to its maximum load. A measured current that does not exceed the minimum threshold may indicate that no field device is connected to the tool 100.

[0079] The power supply 602 can be electrically connected to the communication interface 406 via a resistor 604, which can have any desired resistance (e.g., 200-300 ohms). The resistor 604 can be used to cause a voltage drop sufficient to ensure that the voltage drop at the communication interface 406 remains below a threshold. For example, if the power supply 602 provides a current of 25 mA, the resistor 604 can cause a voltage drop of 6.25 V (i.e., 0.025 A*250 ohms). For example, in the case where the power supply 602 is a 23 V power supply, this may result in a maximum potential output voltage of 16.75 V. As shown, the active communicator 600 also includes a voltage monitor 605, which measures the voltage drop across the resistor 604 and sends the measured voltage drop to the control unit 402. The voltage monitor 605 can be used as a current monitor for the power supply 602. For example, the control unit 604, which can be communicatively coupled to the voltage monitor 605, can rely on the measured voltage drop to calculate the current flowing through the resistor 604. In some cases, active communicator 600 may include an ammeter placed between power source 602 and resistor 604 .

[0080] As described above, the active communicator 600 may include a communication circuit 609, which may include: (i) a DC current controller 610 (e.g., the DC current controller 524 in FIG. 5 ) for transmitting a signal by controlling the current amplitude of an analog DC signal; (ii) a resistor 613 and a voltage monitor 611 for measuring a voltage drop across the resistor 613, which is used by the control unit 402 and the diagnostic manager 662 to calculate a current transmitted by the DC current controller 610; (iii) a resistor network 618 for receiving and interpreting the analog DC signal, and (iv) an FM modem 612 (e.g., the FM modem 504 in FIG. 5 ) for communicating by encoding or decoding a digital FM signal. If desired, one or more components of the communication circuit 609 may be turned off. In general, the DC current controller 610 is used to send a DC signal (e.g., 4-20), the resistor network 618 is used to receive and interpret the DC signal (e.g., 4-20), and the FM modem 612 is used to send and receive a digital signal (e.g., a digital component of a HART signal superimposed on the 4-20 signal). Thus, when connected to an actuator, the circuit manager 661 of the control unit 402 can activate the DC current controller 610 and can disable the resistor network 618. When connected to a transmitter, the circuit manager 662 can activate the resistor network 618 and disable the DC current controller 610. In general, the FM modem 612 will be enabled when connected to both the actuator and the transmitter.

[0081] The DC current controller 610 can be configured to draw a DC current (e.g., 4-20 mA) when the active communicator 600 is connected to the actuator, and can be controlled by the control unit 402 (e.g., in response to user input provided at the UI 410). For example, a user can initiate a command to open a valve to 75% open. Based on the detected input, the control unit 402 can cause the DC current controller 106 to draw a current that corresponds to the command to open the valve to 75% open (e.g., 16 mA). The DC current controller 610 can adjust the current level sharply or change the current level gradually according to the value specified by the user. When the active communicator 600 is connected to the transmitter, the DC current controller 610 can be disconnected from the communication circuit 609 (via a switch not shown) to avoid interfering with the DC current modulation of the transmitter.

[0082] The resistor network 618 can have any desired resistance (e.g., any desired value between 100 ohms and 1000 ohms) and can be adjustable (e.g., by the control unit 402). In some instances, the resistor network 618 has a resistance of 167 ohms. The voltage monitor 616 can measure the voltage drop across the resistor network 618, which can be used to measure the current flowing through the resistor network 618. As an example, in a HART implementation, the voltage monitor 616 can measure a voltage between 3.34V (20mA*167 ohms) and 0.668V (4mA*167 ohms). The digital component of the HART signal, which is typically modulated at 1mA peak-to-peak, can be detected as a peak-to-peak voltage across the resistor network 618 of 0.167V (1mA*167 ohms). Importantly, it is above 0.12V, which is typically the minimum voltage threshold required to read the digital component of the HART signal. Reference Figure 7 Resistor network 618 is described in more detail.

[0083] FM modem 612, similar to FM modem 504, may transmit information and / or receive information using a frequency modulation scheme such as the HART protocol. Capacitor 614 filters out DC current.

[0084] The communication circuit 609 may further include a capacitor 614 in series with the FM modem 612 to filter the DC current so that the FM modem 612 can receive and transmit the AC component of the signal, and a voltage monitor 616 communicatively coupled to the control unit 402 configured to measure the voltage drop across the resistor network 618. The control unit 402, knowing the resistance of the resistor network 618, may calculate the current flowing through the resistor network 618 based on the measured voltage.

[0085] As described above, the communication circuit 609 can be electrically connected to the communication interface 406 to send and receive communication signals. Further, the power supply 602 can be electrically connected to the communication interface 406 to supply power signals to the field device 160 via the communication interface 406. The communication interface 406 may include terminals 631-636 for connecting to one or more field devices, and / or fuses 641 and 642 for limiting the current flowing through the active communicator 600. In general, the field device 160 can be a transmitter that is configured to report a measurement by modulating a DC current (e.g., 4-20 mA), or can be an actuator that is configured to actuate in a specific manner in response to the magnitude of the received DC current (e.g., 4-20 mA).

[0086] The communication interface 406 can be electrically connected to Figure 4The power monitor 408 shown, wherein the power monitor 408 can include a resistor 651 and a voltage monitor 652. The resistor 651 can have a sufficiently low resistance for avoiding a significant voltage drop. In some cases, the resistor 651 has a resistance between 0 and 10 ohms (e.g., 2.43 ohms), which can be selected to minimize the voltage drop on the resistor 651. The voltage monitor 652 can measure the voltage drop across the resistor 651 and send the measured voltage to the control unit 402. The control unit 402 that knows the resistance of the resistor 651 can calculate the current flowing through the resistor 651. In some cases, a fuse 408 can be placed between the terminal 635 and the power monitor.

[0087] In operation, the active communicator 600 can be configured to operate in a "tool-power mode" (i.e., the active communicator 600 supplies power to the connected field device 160) and a "loop-power mode" (i.e., the connected field device 160 relies on, for example, a portable external power source rather than the active communicator 600 for power). The communication interface 406 can include a first set of terminals (e.g., terminals 631 and 632) for the tool power mode and a second set of terminals (e.g., terminals 633 and 634) for the loop power mode. Further, the active communicator 600 can be configured to operate in a "transmitter connection mode" and an "actuator connection mode". Thus, the communication interface 406 can be configured to facilitate the following four different configurations or types of connections: (i) a tool-power transmitter connection, in which the active communicator 600 provides power to the transmitter; (ii) a loop-power transmitter connection, in which the active communicator 600 is connected to a powered transmitter field device (in some cases, the loop of the loop-powered transmitter connection includes a loop resistor to enable communication; in other cases, the loop does not include a loop resistor. When the loop resistor is not present, the tool 100 can activate or adjust the resistor network 618 to provide sufficient loop resistance for communication); (iii) a tool-power actuator connection, in which the active communicator 600 provides power to the actuator; and (iv) a loop-power actuator connection, in which the active communicator 600 is connected to a powered actuator (in some cases, the loop-power actuator includes a DC current controller; in other cases, the loop power actuator does not include a DC current controller).

[0088] For a tool-power transmitter connection, the active communicator 600 may activate a "tool-power" mode and / or a "transmitter connection" mode. Figure 1AAs shown, via screen 122 and / or via button 132), the active communicator 600 can activate one or both of these modes. In some cases, the active communicator 600 can activate the "tool-power" mode in response to detecting that terminals 631 and 632 have been connected to the field device 160. In other cases, the active communicator 600 activates the "tool-power" mode based on input from the user instead. If desired, the active communicator 600 can perform one or more power or communication checks or verifications before activating the "tool-power mode". In some cases, the active communicator 600 can activate the "transmitter connection" mode in response to detecting that the connected field device is a transmitter. In other cases, the active communicator 600 activates the "transmitter connection" mode based on input from the user instead. Further, the active communicator 600 can perform power verification after being able to verify that the field device 160 is behaving as expected (e.g., expected behavior for a transmitter or actuator). The active communicator 600 may also verify that the field device 160 has been connected, power supply limits have not been exceeded, and / or that no circuits have been accidentally shorted.

[0089] For a tool-power transmitter connection, a user may connect a transmitter to terminals 631 and 632. When connected to a transmitter, the current controller 610 may be disconnected from the network via a switch (not shown) because the active communicator 600 does not modulate the DC current to send commands. After the transmitter has been connected, the power supply 602 may ramp up the power. The power may ramp up slowly to avoid current spikes. Current may flow from the power supply 602 through the resistor 604 and the terminal 631 to the transmitter. The transmitter may draw a certain level of baseline current for power (e.g., up to 4 mA). The transmitter may then draw additional current based on its configuration and based on the measurements it has performed (e.g., measured flow, pressure, tank level, etc.). As an example, a current of 4 mA drawn by the transmitter may represent the real-time zero point of the configured measurement range of the transmitter (e.g., 0 gpm), and a current of 20 mA drawn by the transmitter may represent a measurement at the top of the configured measurement range (e.g., 100 gpm). The current drawn between 4-20 mA can represent a proportional measurement within the configured measurement range (e.g., 12 mA = 50 gpm). In some examples, the tool 100 generates a high alarm when a current of 22.5 mA or higher is detected, and / or generates a low alarm when a current of 3.75 mA or lower is detected.

[0090] Current may flow from terminal 631 to the transmitter and through terminal 632, through switch 614 and back. The received current may flow to circuit 609. As described above, capacitor 614 filters out DC current, and when active communicator 600 is connected to the transmitter, DC current controller 610 may be cut off. Thus, the DC component of the received signal flows through resistor network 618, where voltage monitor 616 may measure the voltage drop across resistor network 618 so that control unit 402 may determine the magnitude of the received DC current. Control unit 402 may determine a variable value (e.g., flow rate) based on the determined magnitude.

[0091] Because capacitor 614 allows AC current to pass, the AC component of the signal can flow to FM modem 612. FM modem 612 can then decode the digital signal carried by the received AC component in a manner similar to that described with respect to FM modem 504. Further, FM modem 612 can also send information to the transmitter by encoding the digital signal (superimposed on the DC signal) in a manner similar to that described with respect to FM modem 504.

[0092] For a loop-power transmitter connection, a user may connect a powered transmitter to terminals 633 and 634. Active communicator 600 may respond to user input (e.g., Figure 1A 122 and / or via button 132), activates one or both of "loop power mode" and / or "transmitter connection mode". In some cases, active communicator 600 activates "loop power" mode in response to detecting that terminals 633 and 634 have been connected to a field device (e.g., via link 150). In other cases, active communicator 600 instead activates "loop power" mode based on input from a user. Active communicator 600 may activate "loop-power" mode after verifying that no voltage is present on any other terminals of communication interface 406.

[0093] The tool 100 can include a fuse 642 electrically connected to the terminal 634, which is configured to limit the current to a certain threshold. In some cases, the fuse 642 is not included. In some cases, the fuse 642 is placed between the terminal 634 and ground. In a manner similar to that described with respect to the tool power transmitter connection, the circuit 609 can decode the DC component of the received signal (e.g., 4-20mA) and can modulate and demodulate the AC component of the signal (e.g., a superimposed frequency modulated 1mA peak-to-peak signal) to send and receive information to the transmitter.

[0094] For a tool-power actuator connection, a user may connect an actuator to terminals 631 and 632. Active communicator 600 responds to user input (e.g., via screen 122 and / or via Figure 1A The power source 602 may power the actuator in a manner similar to that described with respect to the tool power transmitter connection.

[0095] In this operating mode, if the DC current controller 610 is disconnected from the circuit 609, a switch (not shown) can activate the DC current controller 610. The DC current controller 610 can draw a DC current (e.g., 4-20 mA), which can be provided by the power supply 602 and can flow through the terminal 631 to the actuator, and then flow through the terminal 632 back to the DC current controller 610. The magnitude of the current serves as a command to the actuator. When the DC current controller 610 is in the working state, the current resistor network 618 and the voltage monitor 616 can be disconnected from the circuit 609 by the control unit 402 via a switch (not shown) because the circuit 609 does not interpret the modulated DC current in this mode.

[0096] Because capacitor 614 allows AC current to pass, the AC component of the received signal can flow to FM modem 612. FM modem 612 can then decode the digital signal carried by the received AC component in a manner similar to that described with respect to FM modem 504, and FM modem 612 can send information to the actuator via the encoded (superimposed on the DC signal) digital signal in a manner similar to that described with respect to FM modem 50.

[0097] For a loop-powered actuator connection, a user may connect a powered actuator to terminals 633 and 634, and active communicator 600 may respond to user input (e.g., Figure 1A As shown, one or both of "loop-power mode" and / or "actuator connection mode" are activated via screen 122 and / or via button 132. In the same manner as described with respect to the tool power transmitter, circuit 609 can modulate the DC component of the signal (e.g., 4-20 mA) to send commands to the actuator, and can modulate and demodulate the AC component of the signal (e.g., a superimposed frequency modulated 1 mA peak-to-peak signal) to send information to the actuator and receive information from the actuator.

[0098] The control unit 402 may include a circuit manager routine 661 for managing the active communicator 600, and / or a diagnostic manager routine 662 for analyzing signals sent and / or received by the active communicator 600. The diagnostic manager 662 may analyze the signals based on measurements obtained from the voltage monitors 605, 611, and / or 616. In some cases, the active communicator 600 includes one or more voltage monitors that measure a voltage drop across one or more of the terminals 631-634 (e.g., across terminals 631 and 632 or across terminals 633 and 634). The diagnostic manager 662 may analyze one or more of these voltage drops before the circuit manager 661 activates (i.e., switches) one or more resistors of the network 618, in order to (i) prevent activation of the resistor network 618 in parallel with the external loop resistor, and / or (ii) manage a multi-step process for activating the resistor network 618.

[0099] First, the circuit manager 661 can protect the user from enabling the resistor network 618 in parallel with the external loop resistor on the external power supply loop, which may cause interference with the loop current and / or losses in communication due to insufficient loop resistance. That is, activating the resistor network 618 when connected in parallel with the external loop resistor can reduce the total loop resistance to a value that is too low to detect and interpret digital communications. To illustrate, in some cases, the resistor network 618 can have a resistance of 250 ohms. The resistance of a typical external loop resistor is 250 ohms. Therefore, if the resistor network 618 is activated in parallel with the external loop resistor, the total loop resistance is reduced to 125 ohms, which may not be enough to cause a readable voltage drop associated with digital communications. For example, HART digital communications, which are usually modulated at 1mA peak-to-peak, generally require a voltage drop of at least 120mVp-p. Therefore, if the total loop resistance is 125 ohms, the error range is very small before the HART digital signal becomes unreadable. To prevent the tool 100 from activating the resistor network 618 in parallel with the external loop resistor, the control unit 402 can cause the FM modem 612 to attempt digital communication upon connection. If digital communication is unsuccessful, the control unit 402 can (e.g., via FIG. 1 and Figure 4 122) prompts the user to activate the resistor network 618. In some cases, the tool 100 may prevent activation of the resistor network 618 in parallel with the loop resistance by prompting the user with one or more questions and / or instructions to cause the user to connect the tool 100 in series with the field device.

[0100] Second, the measured voltage can be used to manage a multi-step process for activating resistor network 618, which can help tool 100 avoid exceeding voltage and / or current thresholds (which otherwise, for example, might cause fuse 642 to blow). For example, diagnostic manager 662 can obtain a voltage measurement from voltage monitor 605 or from a voltage monitor (not shown) across terminals 631 and 632. If diagnostic manager 662 determines that the power supply voltage for power supply 602 or an external power supply exceeds a voltage threshold (e.g., 24V), circuit manager 661 can prevent resistor network 618 from activating. In this case, activation of resistor network 618 may cause excessive current (e.g., greater than 50mA) to flow through resistor network 618, which may blow fuse 642. If the measured power supply voltage is below the voltage threshold, circuit manager 661 can activate resistor network 618 with a resistance of 500 ohms. The diagnostic manager 662 can then measure the current (e.g., based on the measurement from the voltage monitor 616), and if the measured current is below a threshold (e.g., 22.5 mA), the circuit manager 661 can adjust the resistor network 618 to a resistance of 250 ohms or 167 ohms. The situation where the measured current is below the threshold generally indicates that the connected field device is controlling the current.

[0101] Circuit manager 661 can detect a voltage decay across terminals 631 and 632 (e.g., a 0.01V to 0.1V drop every 50 to 100 milliseconds). Circuit manager 661 can take two to ten measurements over a period of 100 milliseconds to 1 second. In response to detecting a voltage decay, circuit manager 661 can give the user the option to immediately activate power supply 602, rather than waiting until the voltage decays to zero.

[0102] When the power supply 602 is disconnected to increase the resistance of the network 618 to bleed voltage from field devices connected to the active communicator 600, the power manager 661 can activate and / or disconnect one or more resistors in the network 618. Bleeding voltage can reduce the required waiting time before the power supply 602 can be reactivated.

[0103] Circuit manager 661 may rely on a temperature sensor (not shown) disposed proximate network 618 to compensate for changes in resistance due to temperature changes, enabling circuit manager 661 to more accurately calculate current based on measurements from voltage monitor 616 .

[0104] Circuit manager 661 may cause DC current controller 610 to change the current gradually. For example, circuit manager 661 may implement a gradual current change in response to a user input specifying a change in current over a particular number of seconds (eg, 1, 2, 3, 4, . . . 60 seconds, etc.).

[0105] The diagnostic manager 662 may perform one or more of the following: loop testing, device simulation, recorder calibration, valve stroke, DCS output check, DCS input check, zero trim calibration, or a check to isolate a cable damage.

[0106] For loop testing, the user can connect the field device to: (i) terminal sets 631 and 632 or terminal sets 633 and 634, and (ii) power monitor 408. Diagnostic manager 662 can cause FM modem 612 to send communication signals to the field device, commanding the field device to draw current at various levels (e.g., 4mA, 12mA, 20mA). Power monitor 408 measures the current sent by the responding field device. Diagnostic manager 662 can cause tool 100 to display the requested current level (current level) and the sent current level (circuit level), so that the user can determine whether the transmitter is responding to the command appropriately.

[0107] For device simulation, the user can connect the tool 100 to a communication link that replaces the field device (e.g., via terminals 631 and 632 of the active communicator 600). The diagnostic manager 662 can cause the DC current controller 610 to send DC current at multiple levels (e.g., in response to user input). The user or a second user can then verify that the connected process controller receives the appropriate value.

[0108] For recorder calibration, the user may wire the tool 100 to an analog recorder and may cause the tool 100 to send a preselected current value to the recorder via the DC current controller 610. The user may then verify that the audio recorder receives the preselected value.

[0109] For valve stroke, the user can wire the tool 100 to the valve. The diagnostic manager 662 can send a 4mA signal to the valve, and the user can set a fully closed stop on the valve (e.g., thereby calibrating the valve so that the fully closed position corresponds to the 4mA signal). The diagnostic manager 662 can (e.g., in response to user input) send a 20mA signal to the valve, and the user can set a fully open stop on the valve (e.g., thereby calibrating the valve so that the fully open position corresponds to the 20mA signal). The diagnostic manager 662 can then perform a step test using the DC current controller 610 (e.g., in response to user input) to transmit current at multiple levels between 4mA and 20mA to verify that the valve is properly calibrated for the 4-20mA signal.

[0110] To check the DCS output, the user can connect the tool 100 to an I / O card that is typically connected to a field device (e.g., an actuator) and is configured to send a 4-20mA signal to the field device for controlling the field device. The user can coordinate with a second user (e.g., via radio) so that multiple commands are sent to the cut-off field device (e.g., to open or close a valve). The diagnostic manager 662 can read the received signal and can display the current measurement so that the user can verify that the I / O card is sending the appropriate signal when attempting to control the field device. The tool 100 can perform a DCS output check using the power monitor 408 (and terminals 635 and 636) or the voltage monitor 616 (and terminals 631 and 632).

[0111] To check the DCS input, the user can connect the tool 100 to an I / O card, which is typically connected to a field device (e.g., a transmitter) and is configured to receive a 4-20 mA signal representing a measurement from the field device. The user can cause the tool 100 to send a signal (e.g., via the DC current controller 610) and can coordinate with a second user to confirm that the controller connected to the I / O card is receiving the appropriate value.

[0112] To perform a zero adjustment calibration, the tool 100 can implement a process similar to implementing a DCS input check. For example, a user can connect the tool 100 to a field device and can cause the field device to run a "device method" that causes the field device to output current at multiple levels. The tool 100 measures and displays the current from the field device. The user then enters the displayed current into the field device so that the field device can calibrate itself based on what it is trying to send and what it actually sends. The tool 100 can activate the power supply 602 to power the field device and the resistor network 618, thereby measuring the current from the field device, and can measure the current across the resistor network 618.

[0113] To isolate a damaged cable, a user may utilize tool 100 to perform voltage measurements at various locations on the cable, at field device terminals, at power supply terminals, etc. A large voltage drop indicates damage.

[0114] Figure 7 yes Figure 6Schematic diagram of resistor network 618 shown, which includes multiple resistors and the resistor network 618 is configured to withstand the failure of one or more resistors within the network 618 without significantly affecting the overall resistance of the network 618. By utilizing multiple resistors, the resistor network 618 can avoid a dramatic increase or decrease in resistance due to a resistor failure, thereby avoiding a dramatic increase or decrease in voltage drop in the circuit. For example, if the resistor network 618 is a single resistor that fails and shorts, the result may be an increased voltage drop across terminals 631 and 632. This increase in voltage drop at terminals 631 and 632 may exceed IS standards and may risk igniting an explosive atmosphere. Further, by utilizing multiple resistors, each individual resistor receives only a portion of the current entering the network 618, which can prevent the resistor from overheating and exceeding IS standards.

[0115] Resistor network 618 may include resistor network 702 and resistor network 704 arranged in parallel, each of which may be disconnected from resistor network 618 via switch 706 and switch 708, respectively. In some examples, the entire resistor network 618 may be disconnected from circuit 609 (e.g., during power-up or when tool 600 is in communication with an actuator). Resistor network 618 may have any desired resistance, for example, in the range of 100 to 300 ohms (e.g., 167 ohms).

[0116] Resistor network 702 may include resistors 712-714 arranged in parallel and may have a total resistance between 200 and 300 ohms (e.g., 250 ohms). For example, each of resistors 712-714 may have a resistance of 750 ohms, giving network 702 a total resistance of 250 ohms. Note that resistor network 702 may have any other combination of multiple resistors (including combinations and / or sub-combinations of resistors arranged in series and / or in parallel) that result in a total resistance of network 702 between 200 and 300 ohms. If desired, resistor network 702 may include a single resistor having a resistance value between 200 and 300 ohms.

[0117] Resistor network 704 may include resistor network 721 and resistor network 723 arranged in series, and may have a total resistance between 400 and 600 ohms (e.g., 500 ohms). Resistor network 721 may include resistors 722 and 724 arranged in parallel, and resistor network 723 may include resistors 726 and 728 arranged in parallel. Each of resistors 722-728 may have a resistance of 500 ohms, which may give each of resistor networks 721 and 723 a resistance of 250 ohms (i.e., 1 / X=1 / 500+1 / 500). Because resistor networks 721 and 723 may be arranged in series, resistor network 704 may have a total resistance of 500 ohms. Note that resistor network 704 may have any other combination of multiple resistors that results in a total resistance between 400 and 600 ohms. For example, resistor network 704 may include two 1000 ohm resistors arranged in parallel, or may include a single resistor having a resistance of 500 ohms.

[0118] With respect to switches 706 and 708, control unit 402 may perform the following operations: (i) actuate switch 706 to disconnect resistor network 702 to increase the resistance of network 618 (i.e., resistance to network 704), or (ii) actuate switch 708 to disconnect resistor network 704 to increase the resistance of network 618 (i.e., resistance to network 702). Control unit 402 may increase the resistance of network 618 to verify that field devices attached to terminals 633 and 634 are current controlled below the rating of fuse 642, or to bleed voltage from active communicator 600 when power supply 602 is disabled.

[0119] In operation, depending on which of the terminals 631-634 is connected to the field device and / or based on whether the active communicator 600 provides power to the field device, the control unit can cut off one of the networks 702 or 704. For example, in some cases, when the active communicator 600 is connected to an externally powered field device, the active communicator 600 can cut off the network 702 or 704 to increase the resistance of the network 618.

[0120] When one or both of the resistor networks 702 and 704 are disconnected from the network 618, the control unit 402 may actuate one or both of the switches 706 and 708 to "activate" both of the networks 702 and 704 and give the resistor network 618 a lower resistance than the resistance of either network 702 or network 704. When operating the active communicator 600 in a "tool power mode" in a hazardous area, a lower resistance may be desired. IS standards require that the output voltage at terminals 631 and 632 be lower than the output voltage that might otherwise be used during normal operation. However, if the voltage at terminals 631 and 632 drops too low, the communication signals sent or received via terminals 631 and 632 may be unreadable. Therefore, it may be advantageous to reduce the resistance of the network 618 from a value that might be used with a conventional communicator (e.g., 250 ohms) to a value that will result in a lower (but still readable) voltage drop across the resistor network 618 (e.g., 167 ohms). In some instances, resistor network 618 may include additional resistor networks (eg, 1000 ohms) and / or switches that may enable tool 100 to activate the resistor network when the power supply voltage exceeds 24V.

[0121] One or both of switches 706 and 708 may be solid state relays, which may provide a number of advantages over typical mechanical relays. For example, solid state relays may switch at lower voltages and lower currents than most mechanical relays, making it easier to maintain the electrical signals generated by tool 100 at levels that comply with IS standards. Additionally, unlike typical mechanical relays, solid state relays typically do not generate sparks when operated. Thus, by using solid state relays with resistor network 618, tool 100 may avoid violating IS standards, which may otherwise be violated in the case of mechanical relays.

[0122] One or more resistors in resistor network 618 may have a large surface area designed to promote efficient heat dissipation. For example, one or more resistors in resistor network 618 may be 2512 sized resistors (e.g., 6.3 mm×3.1 mm×.6 mm). In some cases, one or more resistors in network 618 may be 2010 sized resistors, 2020 sized resistors, and / or 2045 sized resistors. In some cases, one or more resistors (or sub-networks) within resistor network 618 may be rated for 2.5W.

[0123] The tool 100 may include a temperature sensor (not shown) to be used in conjunction with the active communicator 600. For example, the temperature sensor may measure the temperature at or near the resistor network 618, which may be utilized by the control unit 402 when calculating the current flowing through the network 618. Such temperature measurements are beneficial because current calculations based on measurements from the voltage monitor 616 may be inaccurate when temperature changes increase or decrease the resistance of the network 618 to a value different from that assumed by the control unit 402. In short, the temperature sensor enables the control unit 402 to compensate for changes in the resistance of the network 618 due to temperature changes.

[0124] Figure 8A-Figure 12 is a schematic diagram of tool 100, when it includes Figure 6 As shown with active communicator 600, tool 100 is connected to various field devices and I / O devices. Figure 8A-Figure 12 One or more components of the active communicator 600 or tool 100 may not be shown. For example, "off" or inactive components may not be shown. Certain components may be active but may not be shown.

[0125] Fig. 8A An example is illustrated in which the active communicator 600 is connected to the transmitter 805 and in which the active communicator 600 provides power to the transmitter 805 (i.e., a tool powered transmitter connection). In this configuration, a user can connect the active communicator 600 to the transmitter 805 via terminals 631 and 632. The active communicator 600 can power the transmitter 805 via the power supply 602, for example, sending a DC signal of up to 4 mA to the transmitter 805. In addition, the active communicator 600 can participate in unidirectional analog communication and / or bidirectional digital communication with the transmitter 805. In order to participate in unidirectional analog communication, the active communicator 600 can activate a "transmitter connection" mode, in which the active communicator 600 expects the transmitter 805 to communicate by modulating the current amplitude (e.g., between 4-20 mA) of the DC signal provided by the power supply 602. The control unit 402 (not shown) may disconnect the DC current controller 610 (not shown) from the circuit 609 because the transmitter 805, rather than the circuit 609, may modulate the DC current flowing between the transmitter 805 and the tool 100. Note that the FM modem 612 may remain connected to the circuit 609 and may facilitate bidirectional digital communication by: (i) sending information to the transmitter 805 by modulating the frequency of the AC signal superimposed on the DC signal and / or (ii) receiving information from the transmitter 805 by demodulating the frequency modulated AC signal superimposed on the DC signal by the transmitter 805. The diagnostic manager 602 may analyze the signal received from the transmitter 805 based on the measurements obtained from the voltage monitor 616.

[0126] Figure 8B An example is illustrated in which the active communicator 600 is connected to the actuator 855 and in which the active communicator 600 provides power to the actuator 855. In this configuration, a user can connect the active communicator 600 to the actuator 855 via terminals 631 and 632. The active communicator 600 can provide power to the actuator 855 via the power supply 602, for example, sending a DC signal of up to 4 mA to the actuator 855. The active communicator 600 can participate in unidirectional analog communication and / or bidirectional digital communication with the actuator 855. In order to participate in unidirectional analog communication, the active communicator 600 can activate an "actuator connection" mode, in which the active communicator 600 expects the actuator 855 to receive information by interpreting changes in the current amplitude (e.g., between 4-20 mA) of the DC signal provided by the active communicator 600. Because the active communicator 600 may desire that the actuator 855 receive, rather than transmit, the current modulated DC signal, the control unit 402 may disconnect the resistor network 618 (not shown) and the voltage monitor 616 (not shown) from the circuit 609, since the network 618 and the monitor 616 may not be needed to receive and interpret the current modulated DC signal. Note that the FM modem 612 may remain connected to the circuit 609 and may facilitate two-way digital communication by: (i) transmitting information to the actuator 855 by modulating the frequency of the AC signal superimposed on the DC signal, and / or (ii) receiving information from the actuator 855 by demodulating, by the actuator 855, the frequency modulated AC signal superimposed on the DC signal.

[0127] Fig.9A An example is illustrated in which circuit 609 of active communicator 600 may be connected to transmitter 905 and in which transmitter 905 is not powered by active communicator 600. Transmitter 905 may be powered by power supply 910, which may be a portable power supply or a rack mounted power supply. In some instances, transmitter 905 may rely on loop power and power supply 910 for power. A user may connect circuit 609 to transmitter 905 via terminals 633 and 634. Since terminals 631 and 632 are not connected, a closed circuit including power supply 602 is not formed. Circuit 609 may be connected in a manner similar to that described with respect to FIG. Fig. 8A The discussed method involves one-way analog communication and / or two-way digital communication with the transmitter 905. When the user encounters a conventional loop that lacks a loop resistor, Fig.9AThe configuration shown in may be useful. In some instances, tool 100 may be connected to a loop that already has a loop resistor (e.g., connected to the negative terminal of power supply 910). In such a situation, power supply 910 may be wired to the terminals of transmitter 905 as expected for normal operation, and the user may connect terminals 633 and 634 to the terminals of transmitter 905. Alternatively, the user may connect terminals 633 and 634 across an already existing external loop resistor.

[0128] Fig. 9B An example is illustrated in which circuit 609 of active communicator 600 is connected to actuator 955 and in which actuator 955 is not powered by active communicator 600. Actuator 955 can be powered by power supply 960, which can be a portable power supply or a rack-mounted power supply. A user can connect circuit 609 to transmitter 905 via terminals 633 and 634. Since terminals 631 and 632 are not connected, a closed circuit including power supply 602 is not formed. Circuit 609 can be connected in a manner similar to that described with respect to FIG. Figure 8B The discussed manner involves one-way analog communication and / or two-way digital communication with the actuator 955. In some instances, the power supply 960 may include a DC current controller that sends a DC signal (e.g., 4-20mA). In such an instance, the terminals of the power supply 960 can be connected to the terminals of the actuator 955 to form a loop. In addition, in such an instance, the user can connect the tool 100 to the terminals of the actuator 955, effectively placing the tool 100 in parallel with the power supply 960. Advantageously, such a connection enables the user to utilize the tool 100 without disrupting the existing loop between the actuator 955 and the power supply 960.

[0129] Fig.10 An example is illustrated in which the circuit 609 of the tool 100 can be connected to a field device 1010 powered by a power source 1020, and in which the power monitor 408 of the tool 100 can be connected to the field device 1010 in parallel with the power source 1020 so that it can measure electrical characteristics of a signal sent or received by the field device 1010 without disconnecting the field device 1010 from the power source 1020. The field device 1010 can be an actuator or a transmitter; can be powered by the power source 1020; and can include a positive terminal 1012, a negative terminal 1014, and a test terminal 1015. The test terminal 1015 can enable detection of a current flowing through the field device 1010 and / or a voltage across the terminals 1012 and 1014.

[0130] The circuit 609 can be connected to the field device 1010 via terminals 633 and 634, and via the positive terminal 1012 and the negative terminal 1014 of the field device 1010. The power monitor 408 can be connected to the field device 1010 without breaking the loop between the circuit 609 and the field device 1010, so that the user can communicate with the field device 1010 via the circuit 609 at the same time, and can verify that the current, voltage, and / or power measurement values ​​associated with the communication signal between the field device 1010 and the circuit 609 are within the expected range. Advantageously, when the power monitor 408 is used to measure the electrical characteristics of the signal received or sent by the field device 1010, it is not necessary to disconnect the field device 1010 from the power supply 1020. In some cases, (for example, when the field device 1010 is an actuator) the power supply 1020 may include a DC current controller that sends a 4-20mA signal for controlling the field device 1010. In this case, the DC current controller 610 may be disconnected from the circuit and the tool 100 may use the FM modem 612 primarily as a digital communicator.

[0131] Fig.11 An example is illustrated in which the circuit 609 of the tool 100 can be connected to a field device 1105 powered by a power supply 1120, and in which the power monitor 408 of the tool 100 can be connected to the field device 1105 in series with the power supply 1120 so that it can measure the electrical characteristics of the signal sent or received by the field device 1010. The power monitor 408 can be connected to the field device 1105 via terminals 635 and 636. Since the field device 1105 does not include a power supply such as Fig.10 , so the power monitor 408 can be connected in series to the field device 1105. That is, the positive terminal of the power supply 1120 can be disconnected from the positive terminal of the field device 1105, and the first terminal (e.g., terminal 635 or 636) from the power monitor 408 can be connected to the positive terminal of the field device 1105, and the second terminal (e.g., terminal 635 or 636) from the power monitor 408 can be connected to the positive terminal of the power supply. In some cases, the power monitor 408 can be connected in series between the negative terminal of the field device 1105 and a loop resistor (not shown) connected to the negative terminal of the power supply 1120. Typically, such a loop resistor can be found when the field device 1105 is a transmitter. In this case, the resistor network 618 can be cut off from the circuit 609.

[0132] Fig.12An example is illustrated in which the circuit 609 of the active communicator 600 can be used to test the I / O device. Specifically, the circuit 609 can be connected to the AI ​​card 1205 (which can be connected to the transmitter) to verify that the signal sent by the DC current controller 610 (intended to simulate the signal of the transmitter) is properly received by the AI ​​card 1205. In addition, the power monitor 408 can be connected to the AO card 1210 (which can be connected to the controller) to verify the communication sent by the controller 1210 via the AO card 1210.

[0133] Fig.13 is an active communicator 1300 for tool 100 (which may be Figure 4 404), the tool 100 may be electrically connected to the communication interface 406. Figure 1A 100 to perform the following operations: (i) supply power to the field device 160 via a DC signal (e.g., 10-25 mA); and (ii) communicate with the field device 160 via a digital AC signal superimposed on the DC signal. Advantageously, the active communicator 1300 can be used to communicate with and / or diagnose Fieldbus field devices. In addition, unlike typical PTDs configured for AM communication, the active communicator 1300 can measure current and DC and AC voltages at the same terminal set used to communicate with the field device 160. In some cases, the active communicator 1300 can be energy limited and fault tolerant in accordance with IS standards, and enables the active communicator 1300 and the tool 100 to power, communicate with, and / or diagnose field devices and communication links located in hazardous areas.

[0134] The active communicator 1300 can be communicatively coupled to the control unit 402 and can include: (i) a bus 1302 electrically connected to the communication interface 406, (ii) a power supply 1304 configured to send a power signal via the bus 1302, and (iii) a communication circuit 1309 configured to communicate with the field device 160 via the bus 1302. The communication circuit 1309 can be configured to send and receive digital communication signals, which can be amplitude modulated AC signals (e.g., 15-20 mA peak-to-peak).

[0135] The bus 1302 may be referred to as an "internal bus" or "mini bus" and may be provided at least in part on Figure 1AThe bus 1302 may be configured to provide a field device that is electrically connected to a process plant or a process control system. ... The bus 1302 may include switches 1322 and 1324 for disconnecting the terminators 1321 and 1322 from the bus 1302 or for disconnecting the bus 1302 entirely from the active communicator 1300 (e.g., when the active communicator 1300 is connected to a field device that is already connected to a healthy bus). Advantageously, the bus 1302 enables field devices to be tested in isolation, thereby allowing a user to more easily identify the source of a communication problem. For example, a user may utilize the active communicator 1300 to measure a signal sent by an externally powered field device, remove the field device from the external power source (e.g., from the power supply segment), and make the same measurement on the bus 1302, which may be compared to previously obtained measurements.

[0136] The circuit 1309 can communicate with the field device 160 (which can be a fieldbus device) via the bus 1302, and can include an AM modem 1310 connected in series with a capacitor 1314, the combination of which is electrically connected in parallel to a DC current controller or sink 1312. The AM modem 1310 can send and / or receive information to and from the field device 160 using a digital amplitude modulation scheme (such as a fieldbus protocol), and can be the same or similar to the AM modem 514 shown in Figure 5. As an example, the AM modem 1310 can modulate and / or demodulate a 15-20mA (e.g., -10mA to 10mA) signal. The capacitor 1314 can filter the DC current, allowing only digital communication signals to pass to the AM modem 514. The DC current controller 1312 can be configured to draw a DC current sufficient to enable the AM modem 1310 to superimpose the communication signal onto the DC current without requiring the current to drop below 0mA. For example, the DC current controller 1312 may draw a DC current of 11 mA, enabling the AM modem 1310 to superimpose a 20 mA signal on the DC current, causing the total current on the wire connected to the communication interface 406 to vary from 1 mA to 21 mA.

[0137] The communication interface 406 may include terminals 1331-1333. The field device 160 may be connected to terminals 1332 and 1333 to establish a communication link between the field device 160 and the circuit 1309. If the user wishes to use the tool 100 to supply power to the field device 160, the user may place a shunt between the terminal 1331 and the terminal 1332. Placing a shunt between the terminals 1331 and 1332 may activate the bus 1302, which may generate enough load impedance to ensure that the communication signal sent via the terminals 1332 and 1333 is within the expected range so that the AM modem 1310 and / or the field device 160 can interpret the communication signal (e.g., between 0.5 and 1.5 Vpp). The communication interface 406 may include a fuse 1342 electrically connected in series with the terminal 1333, which has a resistance of 11 ohms and is rated for 50 mA. In some cases, the active communicator 1300 does not include the fuse 1342. In some cases, fuse 1342 may be placed between terminal 1333 and ground.

[0138] The power supply 1304 can be configured to supply a power signal at a voltage between 15V and 20V (e.g., 17V) on the bus 1302. The power supply 1304 can be a transformer-based power supply and can "move" its ground relative to the terminal 1333. The power supply 1304 can be configured to limit the voltage drop across the terminals 1332 and 1333 to a threshold consistent with the IS standard. For example, in some cases, the maximum allowable output voltage is limited to 15V when unloaded. The output voltage at full load can be 10.5V. The power supply 1304 can be current limited (e.g., 38mA) to avoid exceeding the voltage and / or power thresholds at the terminals 1331-1333. The active communicator 1300 can include a power regulator 1306 connected in series to the power supply 1304, which is configured to prevent the power supply 1304 (e.g., from the AM modem 1310 and / or the connected field device) from filtering out the communication signal.

[0139] In operation, the active communicator 1300 can operate in a tool power mode and an external power mode. In the tool power mode, the user can connect the field device 160 to the terminals 1332 and 133, and can connect the shunt to the terminals 1331 and 1332 so that current will flow from the terminal 1331 to the terminal 1332 and to the connected field device 160. In the external power mode, the user can connect the field device 160 to the terminals 1332 and 1333, leaving an open circuit between the terminals 1331 and 1332.

[0140] When in external power mode, switches 1332 and 1324 may be activated to disconnect bus 1302 and create an open circuit between terminals 1321-1322 and the wire connecting power regulator 1306 to terminal 1331. Additionally, DC current controller 1312 may be disconnected from circuit 1309 when active communicator 1300 is in external power mode.

[0141] The active communicator 1300 can operate in a communication mode or a diagnostic mode. When in the communication mode, the active communicator 1300 can communicate with the connected field device 160. When in the diagnostic mode, the active communicator 1300 can measure the electrical properties of the signal on the communication bus (e.g., fieldbus segment), and / or can measure the electrical properties of the signal received at the terminal of the field device 160. When in the diagnostic mode, the DC current controller 1312 may not draw significant current. When in the communication mode, the DC current controller 1312 can draw current (e.g., 11mA). In some cases, the active communicator 1300 can operate in the communication mode and the diagnostic mode at the same time.

[0142] If desired, the control unit 402 may disable one or more of the power supply 1304, the power regulator 1306, the terminator 1321 / 1322, and / or the circuit 1309 when a change in voltage or current is detected at the terminals 1331-1333. For example, a detected high voltage across the terminals 1332 and 1333 may indicate that a user has attached a new power supply, which may cause the active communicator 1300 to disable one or more components. As another example, a detected high current at the terminals 1332 and 1333 may indicate that a user has shorted the wires or attempted to add another device, and may cause the active communicator 1300 to disable one or more components. For example, a low voltage measurement may indicate that an externally powered field device has lost power. A low current measurement may indicate that a device has been removed from the terminals 1331-1333.

[0143] The control unit 402 may include a circuit management routine 1361 for managing the active communicator 1300 and / or a diagnostic management routine 1362 for analyzing signals sent and / or received by the active communicator 1300. The circuit manager 1361 may shut down the circuit 1309 to protect the current limited connection from exceeding its current limit due to the current load of the circuit 1309. In addition, the user may interact with the UI 410 to shut down the power supply 1304 at any time.

[0144] Additionally, circuit manager 1361 may compensate for signal measurement errors caused by fuse 1342. That is, circuit manager 1361 may take into account the resistance of fuse 1342 (which may be approximately 11 ohms in some cases) and the resistance of terminals 1321 and 1322 when calculating current measurements based on the voltage drop across bus 1302 associated with the communication signal.

[0145] The diagnostic manager 1362 may perform the following steps: (i) identify field devices, (ii) detect and analyze electrical characteristics of signals transmitted and / or received by the active communicator 1300, (iii) record measurements and / or analysis performed over time, and / or (iv) perform noise spectrum analysis.

[0146] First, the diagnostic manager 1362 can identify field devices connected to the bus 1302 (or to an external bus connected to the active communicator 1300) by tag or device ID. The diagnostic manager 1362 can enable the user to create a user-selectable device list that the user can select during log file creation to define a file name, bus name, and / or location name (e.g., a user-customizable string such as "Tank 157").

[0147] Second, the diagnostic manager 1362 can detect and analyze electrical characteristics of signals sent and / or received by the active communicator 1300. These measurements can be displayed to the user via the display 122 shown in Figures 1 and 4. In addition, the circuit manager 1361 can rely on these measurements to activate or deactivate components of the tool 100 (e.g., to protect the components and / or to ensure compliance with IS standards).

[0148] Third, the diagnostic manager 1362 can record measurements and / or analyses performed over time. For example, the diagnostic manager can create a health report that represents a "snapshot" obtained over time. As an example, a user can utilize the tool 100 to measure signals associated with a given field device on a fairly regular basis (e.g., daily, weekly, etc.). The diagnostic manager 1362 can record these measurements so that factory personnel can identify trends associated with field devices over time. The health report can identify the bus by the tag or ID of the lowest address device on the bus. The health report may include information identifying the user of the tool 100 when the relevant measurement was made, the date of the relevant measurement, the name of the bus or segment where the measurement was made, and / or the name of the location where the measurement was made. The tool 100 can obtain some of this information (e.g., the tag or segment name) from the field device.

[0149] As another example of time-based signal analysis and recording, the diagnostic manager 1362 can create a troubleshooting log for continuously monitoring the signals of a field device over a given period of time. For example, a plant may be experiencing problems with a particular field device (e.g., a communication interruption), but the cause of the problem may not be determined. A user can connect the tool 100 to the field device and leave the tool 100 for an extended period of time (e.g., hours or days). The tool 100 can then measure and record the electrical characteristics of the transmitter and / or the received signal at regular intervals and / or based on a trigger (e.g., a signal that drops above or below a threshold). The user can then analyze the log to identify when the field device encountered a problem, and to determine what may be related to the field device encountering the problem. For example, by comparing the log with historical data collected by the process control system, a user can determine that the interruption experienced by the field device is associated with the start-up of a nearby motor, which causes oscillation that interrupts the communication of the field device. The troubleshooting log can include the same type of information as that included in the health report (e.g., tags, time, date, etc.).

[0150] Fourth, the diagnostic manager 1362 can perform noise spectrum analysis. Specifically, the diagnostic manager 1362 can detect voltages in a small frequency range (e.g., less than 1 kHz) associated with noise, and can display the detected voltages so that a user can identify one or more of the following: (i) the frequency of the noise; (ii) the amplitude of the noise (e.g., average or maximum); and / or (iii) the time at which the noise burst occurred.

[0151] Fig.14A is a schematic diagram of an active communicator 1300 connected to a field device 1405 via an external bus 1420 (ie, external to the active communicator 1300), illustrating an example in which the active communicator 1300 is connected to a field device connected to an operational bus.

[0152] An external power supply 1410 (e.g., a rack-mounted power supply) can supply power to the external bus 1420, and the field device 1405 can draw power from the external bus 1420. The field device 1405 can draw 10-25 mA current for powering. For example, the field device 1405 can draw 20 mA of current, which can be supplied by the power supply 1410. In some cases, multiple field devices can be connected to the bus 1420 and can draw power. For example, three field devices can each draw 20 mA from the bus 1420. In this example, the power supply 1410 can supply 60 mA of current to the bus 1420. A power regulator (not shown) can be placed between the power supply 1410 and the bus 1420.

[0153] Field devices 1405 can be connected to fieldbus segments 1420 via fieldbus spurs. A spur can be a two-wire link connected to segment 1420 via a junction box that can connect multiple other spurs to segment 1420. Isolating the point of failure can be difficult due to the multiple links and connection points associated with fieldbus segment 1420. Advantageously, the communicator 1300 can not only communicate with the field device 1405, but can also "see" what the field device 1405 is "seeing" by connecting to segment 1420 instead of the field device. In short, the tool 100 is a "known good device". If there is a communication problem between the field device and the controller, the tool 100 can be connected to the field device and tested. If the field device works properly when connected to the tool 100, the user of the tool 100 knows that the problem exists "upstream" of the field device (e.g., in a spur, junction box, I / O card, or some other cable or device). Therefore, the user can continue to move upstream and test the communication to isolate the "bad" device or communication link.

[0154] The power supply 1410 may supply power to the field device 1405 via the segment 1420 , as well as to potentially other field devices connected to the segment 1420 .

[0155] Segment 1420 can carry a 10-25mA DC power signal for powering field device 1405 and an AC digital communication signal utilized by field device 1405. In general, multiple other field devices can be connected to segment 1420, each of which draws the 10-25mA DC signal for power. Therefore, the DC current supplied to segment 1405 by power supply 1410 can vary depending on the number of field devices connected to segment 1420 and drawing power. Segment 1420 can include terminators 1422 and 1424. Each of terminators 1422 and 1424 can include, for example, a 100 ohm resistor in series with a 1μF capacitor. Therefore, terminators 1422 and 1424 can block DC current and act as a current shunt for AC communication signals.

[0156] In operation, the active communicator 1300 and the field device 1405 can communicate via a digital signal (e.g., 20 mA peak-to-peak) superimposed on the power signal on the bus 1420. Typically, only one device connected to the bus 1420 can communicate at any given time. For example, if the active communicator 1300, the field device 1405, and two other field devices (not shown) share the bus 1420, only one of the four connected devices can communicate at a given time. The communication on the bus 1420 can be coordinated by a device designated as a link active scheduler (LAS). The LAS can be responsible for passing tokens between devices connected to the bus 1420, where only devices with tokens can communicate on the bus 1420. In some cases, the field device 1405 can be the LAS; in other cases, the tool 100 can be the LAS.

[0157] The LAS maintains a list of all devices that need access to the bus 1420. This list may be referred to as a "real-time device list". In some cases, the bus 1420 may have only a single LAS. A device that can become a LAS may be referred to as a link master. All other devices may be referred to as "basic devices". If desired, the tool 100 may be a link master. When an active communicator 1300 is connected to the bus 1420, the tool 100 may bid to become a LAS. The winning link master (e.g., the link master with the lowest address) may begin operating as a LAS immediately after the bidding process is completed.

[0158] Fig. 14B 1 is a schematic diagram of an active communicator 1300 connected to a field device 1455 via a bus 1302, showing an example in which the active communicator 1300 provides power to the field device 1455. A user can place a shunt 1460 between terminals 1331 and 1332 so that the power supply 1304 can supply power to the bus 1302. The power supply 1302 can be current limited so that the current flowing via the shunt 1460 remains below a maximum threshold consistent with the IS standard. For example, the threshold can be between 35-45 mA. As mentioned, the DC current controller 1312 can draw 11 mA. In addition, a typical field device can draw 10-25 mA. The power supply 1302 can be configured to supply up to 36 mA to ensure that the DC current controller 1312 and the field device 1455 receive sufficient current (i.e., based on the expected potential total current draw of 11 mA+25 mA) while maintaining IS compatibility. The power supply 1304 can be configured to supply a maximum current of 38 mA. A user may utilize the active communicator 1300 to supply power to the field device 1455 , to communicate with the field device 1455 , and / or to perform diagnostics on the field device 1455 while complying with IS standards.

[0159] Fig.15 4 is a view of the communication interface 406 of the tool 100 from the perspective of the outside of the tool 100. As shown, the tool 100 includes the following: Figure 6 and 13 Active communicator 600 and active communicator 1300 are shown. In some cases, tool 100 includes only one of active communicator 600 and active communicator 1300.

[0160] The communication interface 406 may include, for example, Fig.13 The terminals 1331-1333 shown and Figure 6 Terminals 631 - 636 are shown, which may be arranged as terminal sets 1501 - 1504 .

[0161] In operation, a user may connect terminal set 1501 to a field device configured to communicate according to an AM communication scheme such as the Fieldbus protocol. A user may utilize terminal set 1501 when connecting tool 100 to a field device that relies on an external (i.e., external to tool 100) power source (e.g., a rack-mounted power source typically found in a factory environment). If a user desires to power a field device using tool 100, the user may connect terminals 1331 and 1332 using a shunt.

[0162] As another example, a user can connect terminal set 1502 to a field device that requires power and is configured to communicate according to a DC current signaling scheme (e.g., 4-20 mA) and / or according to a digital FM communication scheme (e.g., HART protocol) and requires power. Alternatively, if a user wants to connect tool 100 to a similarly configured field device that is already powered by an external power source, the user can connect the field device to terminal set 1503. The user can also connect terminal set 1502 to a field device or to a communication link connected to the field device to detect electrical characteristics (e.g., current, voltage) of a signal sent by the field device or received by the field device.

[0163] Finally, the user can connect the terminal set 1504 to the field device to detect the electrical characteristics (e.g., current, voltage) of the signal sent by the field device or received by the field device. The user can also connect the terminal set 1504 to a communication link (e.g., a HART loop or a fieldbus segment) to detect the electrical characteristics of the signal sent via the communication link. In some cases, the power monitor 408 connected to the terminal set 1504 only measures the current.

[0164] As shown, the communication interface 406 enables the tool 100 to communicate with or diagnose field devices configured according to different protocols. Thus, a user can carry the tool 100 to service a variety of different types of field devices, rather than carrying multiple dedicated tools.

Claims

1. A portable field maintenance tool comprising: (A) communications circuits; (B) power supply; (C) a housing that houses the communication circuit and the power supply; (D) a first terminal set electrically connected to the communication circuit and isolated from the power supply, the first terminal set being electrically connectable to a field device external to the housing to transmit a communication signal from the communication circuit to the field device without transmitting a power signal from the power supply; and (E) a second terminal set electrically connected to the communication circuit and electrically connected to the power supply, the second terminal set being electrically connectable to the field device to send a composite signal, the composite signal comprising: (i) the communication signal from the communication circuit, and (ii) the power signal from the power supply.

2. The portable field maintenance tool according to claim 1, wherein: The communication circuitry and the power supply are each configured to maintain intrinsically safe energy levels.

3. The portable field maintenance tool according to claim 1, wherein: The communication signal is a digital amplitude modulated (AM) signal.

4. The portable field maintenance tool according to claim 3, wherein: The communication signal is a fieldbus signal.

5. The portable field maintenance tool according to claim 1, wherein: The first terminal set includes a first terminal and a second terminal, and wherein the second terminal set includes the first terminal, the second terminal, and a third terminal.

6. The portable field maintenance tool according to claim 1, wherein: The first terminal set includes a first terminal and a second terminal, and wherein the second terminal set includes a third terminal and a fourth terminal.

7. The portable field maintenance tool of claim 1, further comprising one or more terminators electrically connected in parallel to the communication circuit.

8. A method for communicating with a field device, the method comprising: communicatively connecting a field device to a portable field maintenance tool, the portable field maintenance tool including communication circuitry for communicating with the field device and a power source for powering the field device; when the field device is connected to the first set of terminals of the portable field maintenance tool, transmitting a communication signal from the communication circuit to the field device without transmitting a power signal from the power supply; as well as When the field device is connected to the second terminal set of the portable field maintenance tool, a composite signal is sent to the field device, the composite signal including: (i) the communication signal from the communication circuit, and (ii) the power signal from the power source within the portable field maintenance tool.

9. The method according to claim 8, wherein: Sending the composite signal to the field device comprises: A digital AM signal superimposed on the DC power signal is sent to the field device.

10. The method according to claim 8, wherein: communicatively connecting the field device to the portable field maintenance tool includes placing a shunt between one of the first terminal and the second terminal and the third terminal; as well as After the shunt has been placed between one of the first and second terminals and the third terminal, the field device is connected to the second set of terminals by connecting the field device to the first set of terminals.

11. A portable field maintenance tool comprising: (A) Housing; (B) a communication interface disposed in the housing and electrically connectable to a field device external to the housing and located in a process control environment; (C) a communication bus disposed in the housing, electrically connected to the communication interface and configured to carry a composite signal, the composite signal comprising: (i) a communication signal transmitted to or from the field device, and (ii) bus power for powering the field device; (D) a switch component disposed in the housing and electrically connected to the communication bus; and (E) a power source disposed in the housing and electrically connected to the switch component; Wherein, the switch component is actuatable to: (i) electrically connect the power supply arranged in the housing to the communication bus, thereby supplying the bus power to the communication bus to power the field device outside the housing, and (ii) electrically disconnect the power supply from the communication bus, thereby preventing the power supply from supplying the bus power to the communication bus.

12. The portable field maintenance tool of claim 11, wherein: The switch component includes one or more solid-state relays that, when activated, electrically connect the power source to the communication bus or electrically disconnect the power source from the communication bus.

13. The portable field maintenance tool of claim 11, wherein: The switch component includes circuitry that turns off the power supply when activated.

14. The portable field maintenance tool of claim 11, further comprising energy measurement circuitry that measures one or more electrical characteristics of the composite signal over the communications bus.

15. The portable field maintenance tool of claim 14, further comprising a control unit that actuates the switch component based on the one or more electrical characteristics.

16. A method of controlling bus power provided by a portable field maintenance tool, the method comprising: communicatively connecting a field device to a communication bus of a portable field maintenance tool, the communication bus being configured to carry a composite signal comprising: (i) a communication signal transmitted to or from the field device, and (ii) bus power for powering the field device; and Actuating a switch component electrically connected to both the communication bus and a power source of the portable field maintenance tool to: (i) electrically connecting the power source of the portable field maintenance tool to the communication bus, thereby supplying the bus power to the communication bus to power the field device, or (ii) electrically disconnecting the power supply from the communications bus, thereby preventing the power supply from supplying the bus power to the communications bus.

17. The portable field maintenance tool of claim 16, wherein: The communication signal is a digital amplitude modulated (AM) signal.

18. A portable field maintenance tool comprising: case; a communication bus disposed within the housing, the communication bus including a terminal set accessible outside the housing and electrically connectable to a field device external to the housing via a wired link; a communication circuit disposed in the housing and electrically connected to the communication bus, the communication circuit receiving a signal from the field device or sending a signal to the field device via the communication bus; as well as An energy measurement circuit is disposed in the housing and electrically connected to the communication bus, the energy measurement circuit measuring an electrical characteristic of the signal transmitted or received via the communication bus.

19. The portable field maintenance tool of claim 18, further comprising: A power supply supplies power to the field device via the communication bus.

20. The portable field maintenance tool of claim 19, further comprising: A control unit is communicatively coupled to the energy measurement circuit and the power supply, the control unit controlling the power supply based on the measured electrical characteristic.

21. The portable field maintenance tool of claim 18, wherein: When the energy measurement circuit measures the electrical characteristic of the signal, the communication circuit simultaneously receives or transmits the signal.

22. The portable field maintenance tool of claim 18, further comprising: a control unit communicatively coupled to the energy measurement circuit, the control unit being configured to: (i) causing the energy measurement circuit to obtain a plurality of measurements of the electrical characteristic over a specific period of time; as well as (ii) recording the plurality of measurement results by storing each of the plurality of measurement results in a memory.

23. The portable field maintenance tool of claim 18, wherein: The measured electrical characteristic is a frequency or an amplitude associated with noise on the communication bus, and wherein the portable field maintenance tool further comprises: Display; and A control unit is communicatively coupled to the display and the energy measurement circuit, the control unit being configured to cause the display to display the frequency or the amplitude associated with the noise on the communication bus.

24. A method of communicating with a field device and monitoring a signal sent or received by the field device, the method comprising: electrically connecting the field device to a communication bus of the portable field maintenance tool via a terminal set of the portable field maintenance tool; sending a signal to the field device or receiving a signal from the field device via the communication bus; as well as While the signal is being transmitted or received, an electrical characteristic of the signal transmitted or received via the communication bus is measured.

25. The method according to claim 24, wherein: The electrical characteristic is a voltage of the signal on the communication bus, and wherein the method further comprises: The portable field maintenance tool is disabled when a voltage of the signal on the communications bus exceeds a maximum voltage threshold.

26. The method of claim 24, further comprising: supplying power from the portable field maintenance tool to the field device via the communication bus; as well as The supplied power is adjusted to prevent the voltage on the communication bus from exceeding a maximum voltage threshold.

27. The method according to claim 24, wherein: The signal is a composite signal including power for the field device and a digital AM communication signal superimposed on the power.

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