A HART device communicator with automatic loop switching

Abstract

The present invention discloses a HART device communicator for automatically switching loops, comprising: a detection unit connected to an external HART device and used to detect interface parameters of the external HART device; a data processing unit connected to the detection unit and used to determine the type of the external HART device based on the parameters detected by the detection unit; a loop switching unit connected to the external HART device and the data processing unit and controlled by the data processing unit, used to perform loop switching; and a voltage conversion unit, which is disconnectably connected to the loop switching unit. When the communicator communicates with the HART device and is connected to the loop, the detection unit automatically detects the interface parameters of the external HART device and sends them to the data processing unit. The data processing unit determines the type of the external HART device based on the acquired parameters, thereby controlling the loop switching unit to adjust to a corresponding state, so that the communicator establishes communication with the external HART device.

Description

Technical Field

[0001] The invention belongs to the technical field of HART device communication devices, and in particular relates to a HART device communicator with automatic switching loops. Background Art

[0002] HART (Highway Addressable Remote Transducer) is a communication protocol for field smart instruments and control room equipment launched by Rosement in the United States in 1985. HART devices provide communication with relatively low bandwidth and moderate response time. After more than 10 years of development, HART technology has become very mature abroad and has become the industrial standard for global smart instruments.

[0003] At present, in different HART device testing or application environments, HART devices have application scenarios where only HART communication is used to configure device parameters, or where current and HART communication information need to be monitored simultaneously. For existing general HART communicators, different wiring is required for different application scenarios, and communication resistors or power distribution power supplies are connected in series; HART communicators with power distribution cannot be directly connected to HART instruments that require current monitoring, such as HART instruments that have been installed online or HART instruments that need current calibration during the production process. Therefore, under the current situation, different wiring or different HART communicators are required for different application scenarios, which is cumbersome to operate and has poor versatility. Summary of the invention

[0004] To solve the above problems, the purpose of the present invention is to provide a HART device communicator with automatic switching loops, which can automatically detect the current application wiring environment, switch the loop directly to communicate with the HART device, avoid additional wiring, and achieve fast and convenient connection with the HART device.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A HART device communicator for automatically switching loops, comprising:

[0007] A detection unit, connected to an external HART device, for detecting interface parameters of the external HART device;

[0008] A data processing unit connected to the detection unit, and configured to determine the type of the external HART device based on the parameters detected by the detection unit;

[0009] A loop switching unit, connected to the external HART device and the data processing unit and controlled by the data processing unit, for performing loop switching;

[0010] A voltage conversion unit is disconnectably connected to the circuit switching unit.

[0011] Preferably, the communicator further comprises a USB to serial port unit connected to the voltage conversion unit, and the data processing unit is connected to an external PC via the USB to serial port unit.

[0012] Preferably, the detection unit includes a first switch, a first resistor, a second resistor and a third resistor, the first switch and the first resistor are connected in series and then connected in parallel with the external HART device, and the second resistor and the third resistor are connected in series and then connected in parallel with the external HART device.

[0013] Preferably, the data processing unit includes an MCU processor and a modem; the MCU processor is connected to the detection unit, and is used to obtain the interface parameters of the external HART device and determine the type of the external HART device; the modem is connected to the loop switching unit and the MCU processor, and is used to modulate and demodulate the signal and communicate with the external PC through the MCU processor and the USB to serial port unit.

[0014] Preferably, the loop switching unit includes a fourth resistor, a second switch, a third switch and a single-pole double-set switch, the fourth resistor is connected to the second output end of the external HART device and the first input end of the modem, the second switch is connected in parallel with the fourth resistor, the input end of the voltage conversion unit is connected to the first contact of the single-pole double-set switch through the third switch, the first contact of the single-pole double-set switch is connected to the first output end of the external HART device, the second contact of the single-pole double-set switch is connected to the second input end of the modem, and the third contact of the single-pole device switch is connected to the input end of the fourth resistor, wherein the second contact of the single-pole double-set switch is a static contact.

[0015] Based on the same concept as above, the present invention also provides a method for detecting an external HART device by the communicator, characterized in that it comprises the following steps:

[0016] Disconnect the first switch and detect a first voltage between the second resistor and the third resistor;

[0017] Closing the first switch to detect a second voltage between the second resistor and the third resistor;

[0018] The type of the external HART device is determined based on the values ​​of the first voltage and the second voltage.

[0019] Based on the same concept as above, the present invention also provides an automatic switching method for the communicator loop, characterized in that, when the external HART device is of the first type, the first switch and the second switch are disconnected, the third switch is closed, and the moving contact of the single-pole double-set switch is connected to the third contact; when the external HART device is of the second type, the first switch and the third switch are disconnected, the second switch is closed, and the moving contact of the single-pole double-set switch is connected to the first contact; when the external HART device is of the third type, the first switch and the second switch are closed, the third switch is disconnected, and the moving contact of the single-pole double-set switch is connected to the first contact.

[0020] Based on the same concept as above, the present invention also provides an electronic device, characterized in that it includes a memory, wherein the memory is used to store a processing program;

[0021] A processor implements the above-mentioned method for detecting an external HART device and the loop automatic switching method when the processor executes the processing program.

[0022] Based on the same concept as above, the present invention also provides a readable memory, characterized in that a processing program is stored on the readable storage medium, and when the processing program is executed by the processor, the above-mentioned method for detecting an external HART device and the automatic loop switching method are implemented.

[0023] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0024] The communicator of the present invention communicates with the HART device. When the loop is connected, the detection unit automatically detects the interface parameters of the external HART device and sends them to the data processing unit. The data processing unit determines the type of the external HART device according to the acquired parameters, thereby controlling the loop switching unit to adjust to the corresponding state, so that the communicator establishes communication with the external HART device. The communicator MCU collects the voltage at the connection point, disconnects the S1 switch, performs self-test on the current wiring loop, and according to the detection result, turns on the corresponding switch to establish communication with the HART device again. When the work stops, when the serial port stops sending data commands, the loop automatically exits and restores the default state of the switch. Automatic detection is achieved without cumbersome wiring and judgment before wiring. In addition, it is equipped with a power supply circuit, and HART communication can still be established without external power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0026] Figure 1A schematic diagram of the circuit principle of a HART device communicator for automatically switching loops of the present invention;

[0027] Figure 2 It is an internal equivalent circuit diagram of a first state of a HART device communicator for automatically switching loops of the present invention;

[0028] Figure 3 It is a schematic diagram of the first state operation of a HART device communicator for automatically switching loops of the present invention;

[0029] Figure 4 It is an internal equivalent circuit diagram of the second state of a HART device communicator with an automatic switching loop of the present invention;

[0030] Figure 5 A schematic diagram of the second state operation of a HART device communicator for automatically switching loops according to the present invention;

[0031] Figure 6 It is an internal equivalent circuit diagram of the third state of a HART device communicator with an automatic switching loop of the present invention;

[0032] Figure 7 The present invention is a schematic diagram of the third state operation of a HART device communicator with automatic switching loops. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0034] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0035] The HART protocol uses the FSK frequency shift keying signal based on the Bell202 standard, superimposing an audio digital signal with an amplitude of 0.5mA on the low-frequency 4-20mA analog signal for two-way digital communication, and the data transmission rate is 1.2kbps. Since the average value of the FSK signal is 0, it does not affect the size of the analog signal transmitted to the control system, ensuring compatibility with the existing analog system. In the HART protocol communication, the main variables and control information are transmitted by 4-20mA. If necessary, other measurements, process parameters, equipment configuration, calibration, and diagnostic information are accessed through the HART protocol.

[0036] Generally, HART communicators are used in the following wiring scenarios:

[0037] 1. The HART device has power supply, but there is no communication resistor 250R in the loop. Figure 4 A common scenario is with installed factory HART devices.

[0038] 2. There is a 250R resistor in the HART device loop, and communication with the device is required. Figure 3 This scenario is common in testing and production processes, and requires both monitoring device current through communication resistors and communicating with the device.

[0039] 3. HART equipment has no power supply loop, and the equipment needs to be powered and communicated. Figure 2 This scenario is common in device unpacking and debugging scenarios, and the device has no external circuits.

[0040] In view of the above three wiring scenarios, the present invention designs a detection and automatic switching circuit so that communication can be automatically established regardless of the application scenario.

[0041] Example 1

[0042] like Figure 1 As shown, the HART device communicator of the automatic switching loop includes:

[0043] A detection unit, connected to an external HART device, for detecting interface parameters of the external HART device;

[0044] A data processing unit connected to the detection unit, and configured to determine the type of the external HART device based on the parameters detected by the detection unit;

[0045] A loop switching unit, connected to the external HART device and the data processing unit and controlled by the data processing unit, for performing loop switching;

[0046] A voltage conversion unit is disconnectably connected to the circuit switching unit.

[0047] When the communicator communicates with the HART device and is connected to the loop, the detection unit detects the interface parameters of the external HART device and sends them to the data processing unit. The data processing unit determines the type of the external HART device based on the acquired parameters, thereby controlling the loop switching unit to adjust to the corresponding state, so that the communicator establishes communication with the external HART device.

[0048] In a possible technical solution of this embodiment, the communicator also includes a USB to serial port unit connected to the voltage conversion unit, and the data processing unit is connected to an external PC through the USB to serial port unit to realize the conversion of a traditional serial port device into a plug-and-play USB device.

[0049] In a possible technical solution of this embodiment, the detection unit includes a first switch, a first resistor, a second resistor and a third resistor, the first switch and the first resistor are connected in series and then connected in parallel with the external HART device, the second resistor and the third resistor are connected in series and then connected in parallel with the external HART device. The input end of the data processing unit is connected to the output end of the second resistor and collects the voltage of the connection point.

[0050] In a possible technical solution of this embodiment, the data processing unit includes an MCU processor and a modem; the MCU processor is connected to the detection unit, and is used to obtain the interface parameters of the external HART device and determine the type of the external HART device; the modem is connected to the loop switching unit and the MCU processor, and is used to modulate and demodulate the signal and communicate with the external PC through the MCU processor and the USB to serial port unit.

[0051] In a possible technical solution of this embodiment, the loop switching unit includes a fourth resistor, a second switch, a third switch and a single-pole double-set switch, the fourth resistor is connected to the second output end of the external HART device and the first input end of the modem, the second switch is connected in parallel with the fourth resistor, the input end of the voltage conversion unit is connected to the first contact of the single-pole double-set switch through the third switch, the first contact of the single-pole double-set switch is connected to the first output end of the external HART device, the second contact of the single-pole double-set switch is connected to the second input end of the modem, and the third contact of the single-pole device switch is connected to the input end of the fourth resistor, wherein the second contact of the single-pole double-set switch is a static contact.

[0052] In the default state of the communicator, the first switch and the second switch are in a closed state, the third switch is in an open state, and the single-pole double-set switch is connected to a first contact.

[0053] When connected to the loop, if the voltage U of the connection point is 0V regardless of whether the first switch is closed or open, the MCU processor determines that the external HART device is of the first type, that is, the HART device has no power supply loop, and the device needs to be powered and communicated. This scenario is common in the device unpacking and debugging scenario, and the device has no external circuit. Then the communicator is controlled to switch to the first state, that is, the first switch and the second switch are disconnected, the third switch is closed, and the moving contact of the single-pole double-set switch is connected to the third contact.

[0054] like Figure 2-Figure 3 As shown, Figure 2 When the MCU processor determines that the external HART device is of the first type, the internal equivalent circuit of the processor. Figure 3 This is a schematic diagram of the working circuit of the communicator at this time.

[0055] When connected to the loop, if the first switch is disconnected, the voltage of the connection point is 1V≤U≤5V, and when the first switch is closed, the voltage of the connection point is 0.5V≤U≤2.5V, then the MCU processor determines that the external HART device is of the second type, that is, there is a 250R resistor in the HART device loop, and communication with the device is required. This scenario is common in testing and production processes, and it is necessary to rely on communication resistance to monitor device current and communicate with the device. Then the communicator is controlled to switch to the first state, that is, the first switch is disconnected, the second switch is closed, the third switch is disconnected, and the moving contact of the single-pole double-set switch is connected to the first contact.

[0056] like Figure 4-Figure 5 As shown, Figure 4 When the MCU processor determines that the external HART device is of the second type, the internal equivalent circuit of the processor. Figure 5 It is a schematic diagram of the working circuit of the communicator at this time.

[0057] When connected to the loop, if the first switch is open, the voltage U of the connection point is greater than 10V, and when the first switch is closed, the voltage 1V≤U≤5V of the connection point, then the MCU processor determines that the external HART device is of the third type, that is, the HART device has a power supply, but there is no communication resistor 250R in the loop, which is a common scenario in factory HART devices that have been installed. Then the communicator is controlled to switch to the first state, that is, the first switch and the second switch are closed, the third switch is open, and the moving contact of the single-pole double-set switch is connected to the first contact.

[0058] like Figure 6-Figure 7 As shown, Figure 6 When the MCU processor determines that the external HART device is of the third type, the internal equivalent circuit of the processor. Figure 7 It is a schematic diagram of the working circuit of the communicator at this time.

[0059] The type of the current external HART device is determined by automatic detection, and the state of the communicator is switched to complete communication with the HART device in different wiring scenarios.

[0060] Example 2

[0061] Based on the same concept as above, the present invention also provides a method for detecting an external HART device by the communicator, characterized in that it comprises the following steps:

[0062] Disconnect the first switch and detect a first voltage between the second resistor and the third resistor;

[0063] Closing the first switch to detect a second voltage between the second resistor and the third resistor;

[0064] The type of the external HART device is determined based on the values ​​of the first voltage and the second voltage.

[0065] Example 3

[0066] Based on the same concept as above, the present invention also provides an automatic switching method for the communicator loop, characterized in that, when the external HART device is of the first type, the first switch and the second switch are disconnected, the third switch is closed, and the moving contact of the single-pole double-set switch is connected to the third contact; when the external HART device is of the second type, the first switch and the third switch are disconnected, the second switch is closed, and the moving contact of the single-pole double-set switch is connected to the first contact; when the external HART device is of the third type, the first switch and the second switch are closed, the third switch is disconnected, and the moving contact of the single-pole double-set switch is connected to the first contact.

[0067] Example 4

[0068] Based on the same concept as above, the present invention also provides an electronic device, characterized in that it includes

[0069] A memory, the memory being used to store a processing program;

[0070] A processor implements the above-mentioned method for detecting an external HART device and the loop automatic switching method when the processor executes the processing program.

[0071] Example 5

[0072] Based on the same concept as above, the present invention also provides a readable memory, characterized in that a processing program is stored on the readable storage medium, and when the processing program is executed by the processor, the above-mentioned method for detecting an external HART device and the automatic loop switching method are implemented.

[0073] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A HART device communicator with automatic switching loop, characterized in that: include: A detection unit, connected to an external HART device, for detecting interface parameters of the external HART device; A data processing unit connected to the detection unit, and configured to determine the type of the external HART device based on the parameters detected by the detection unit; A loop switching unit, connected to the external HART device and the data processing unit and controlled by the data processing unit, for performing loop switching; a voltage conversion unit, having a disconnectable connection to the circuit switching unit; The loop switching unit includes a fourth resistor, a second switch, a third switch and a single-pole double-set switch, the fourth resistor is connected to the second output end of the external HART device and the first input end of the modem, the second switch is connected in parallel with the fourth resistor, the input end of the voltage conversion unit is connected to the first contact of the single-pole double-set switch through the third switch, the first contact of the single-pole double-set switch is connected to the first output end of the external HART device, the second contact of the single-pole double-set switch is connected to the second input end of the modem, and the third contact of the single-pole double-set switch is connected to the input end of the fourth resistor, wherein the second contact of the single-pole double-set switch is a static contact.

2. The HART device communicator for automatic switching loop according to claim 1, characterized in that: The communicator further comprises a USB to serial port unit connected to the voltage conversion unit, and the data processing unit is connected to an external PC via the USB to serial port unit.

3. The HART device communicator for automatic switching loop according to claim 2, characterized in that: The detection unit includes a first switch, a first resistor, a second resistor and a third resistor. The first switch and the first resistor are connected in series and then connected in parallel with an external HART device. The second resistor and the third resistor are connected in series and then connected in parallel with the external HART device.

4. The HART device communicator for automatic switching loop according to claim 2 or 3, characterized in that: The data processing unit includes an MCU processor and a modem; the MCU processor is connected to the detection unit and is used to obtain the interface parameters of the external HART device and determine the type of the external HART device; The modem is connected to the loop switching unit and the MCU processor, and is used for modulating and demodulating signals and communicating with an external PC through the MCU processor and the USB to serial port unit.

5. A method for detecting an external HART device by the communicator according to claim 3, characterized in that: The steps include: Disconnect the first switch and detect a first voltage between the second resistor and the third resistor; Closing the first switch to detect a second voltage between the second resistor and the third resistor; The type of the external HART device is determined based on the values ​​of the first voltage and the second voltage.

6. A method for automatically switching a communicator circuit as claimed in claim 3, characterized in that: When the external HART device is of the first type, the first switch and the second switch are disconnected, the third switch is closed, and the moving contact of the single-pole double-set switch is connected to the third contact; when the external HART device is of the second type, the first switch and the third switch are disconnected, the second switch is closed, and the moving contact of the single-pole double-set switch is connected to the first contact; when the external HART device is of the third type, the first switch and the second switch are closed, the third switch is disconnected, and the moving contact of the single-pole double-set switch is connected to the first contact.

7. An electronic device, characterized in that: include A memory, the memory being used to store a processing program; A processor, wherein when executing the processing program, the processor implements the method for detecting an external HART device as claimed in claim 5 or the automatic loop switching method as claimed in claim 6.

8. A readable memory, characterized in that: The readable storage medium stores a processing program, and when the processing program is executed by the processor, the method for detecting an external HART device according to claim 5 or the automatic loop switching method according to claim 6 is implemented.

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