Load adapter module for wireless discrete input / output field devices

Abstract

A wireless field device (12) for use in industrial processes includes an input / output terminal (40) configured to couple to a process interface element (16). A discrete input / output channel (24), when configured as a discrete input channel, is configured to receive discrete input signals from the process interface element (16) through the input / output terminal (40). The discrete input / output channel (24), when configured as a discrete output channel, is further configured to provide discrete outputs to the process interface element (16) through the input / output terminal (40). A wireless communication circuit (48) transmits and receives information. A controller (44), when the discrete input / output channel (24) is configured as a discrete output channel, provides discrete output signals to the process interface element (16) in response to information received by the wireless communication circuit (48), and is further configured to receive discrete input signals from a process variable sensor (16) and provide outputs in response using the wireless communication circuit (48) when the discrete input / output channel (24) is configured as a discrete input channel. The external power input (Ext+ / -) is connected to the external power supply (102). The load adapter module (200) includes a switch (M1) coupled to the discrete output signal and the external power input, configured to connect the process interface element (16) to the external power supply (102) in response to the discrete output signal.

Description

Technical Field

[0001] The present invention relates to a type of field device used for controlling or monitoring industrial processes. More particularly, the present invention relates to a wireless industrial process field device having discrete input and discrete output (DIO) channels.

[0002] Industrial processes are employed in the monitoring and production of process materials and fluids such as oil, paper pulp, etc. To monitor the operation of an industrial process, process variable transmitters are employed. A process variable transmitter measures a process variable and transmits process variable information to a central location. Exemplary process variables include flow rate, temperature, pressure, fluid level, etc. A process variable transmitter is an example of a field device. Another exemplary field device is a process control device. A process control device is used to control the operation of a process by actuating control elements. For example, a process control device can actuate a motor to adjust the position of a valve, control the operation of a pump, actuate a heating element, etc. A process control device can receive its commands from a central location.

Summary of the Invention

Problems to be Solved by the Invention

[0003] One type of field device is a discrete input / output (I / O) device. A discrete I / O, i.e., a DIO device, typically includes a plurality of input channels and / or output channels and can be configured to operate as a process variable transmitter and as a process control device. The input channels can be used, for example, to detect the closing or opening of a switch such as a liquid level switch. The output channels can be used, for example, to control an external load. However, the output channels can typically only connect the load to the low side of the power supply.

Means for Solving the Problems

[0004] Wireless field devices for use in industrial processes include input / output terminals configured to couple to process interface elements. A discrete input / output channel, when configured as a discrete input channel, is configured to receive discrete input signals from process interface elements through its input / output terminals. The discrete input / output channel, when configured as a discrete output channel, is further configured to provide discrete outputs to process interface elements through its input / output terminals. A wireless communication circuit transmits and receives information. A controller, when the discrete input / output channel is configured as a discrete output channel, is configured to provide discrete output signals to process interface elements in response to information received by the wireless communication circuit; and, when the discrete input / output channel is configured as a discrete input channel, is configured to receive discrete input signals from process variable sensors and, using the wireless communication circuit, provide outputs in response. An external power input couples to an external power supply. A load adapter module includes a switch coupled to the discrete output signals and the external power input, configured to connect the process interface elements to the external power supply in response to the discrete output signals.

[0005] This summary is provided to present a simplified overview of the conceptual options further described in the following "Modes for Carrying Out the Invention." This "Summary of the Invention" is not intended to identify any major or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to any implementation that solves any or all of the defects mentioned in the "Background Art." [Brief explanation of the drawing]

[0006] [Figure 1] This is a simplified diagram of an industrial process control system including discrete input / output (DIO) field devices. [Figure 2A]Figure 1 shows the discrete input / output channels of the field device configured as input channels. [Figure 2B] Figure 1 shows the discrete input / output channels of the field device configured as an output channel. [Figure 2C] Figure 1 shows a field device configured with discrete input / output channels as output channels, using an external power supply. [Figure 3] Figure 1 is a simplified circuit diagram showing the discrete input / output field device along with its eight input and output channels, external power supply, and battery connection terminals. [Figure 4A] This block diagram shows a load adapter module in one configuration example, coupled to a 3-terminal discrete input / output (DIO) field device. [Figure 4B] This block diagram shows a load adapter module in one configuration example, coupled to a 2-terminal discrete input / output (DIO) field device. [Figure 5] This is a perspective view of a load adapter module relating to one configuration example. [Figure 6] Figure 5 is a perspective view showing the load adapter module mounted on the front panel of a DIO field device. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Elements identified by the same or similar reference numerals indicate the same or similar elements. Some components shown in each figure may be omitted for clarity. Various embodiments of this disclosure may be carried out in many different forms and should not be construed as being limited to any particular embodiment described herein. Rather, these embodiments are provided to make this disclosure complete and comprehensive and to fully convey the scope of this disclosure to those skilled in the art.

[0008] The field devices described herein can receive discrete inputs from sensors in industrial processes related to process variables. Sensors are coupled to the terminals of the field device. Furthermore, the terminals of the field device can be configured to provide separate outputs to control elements in the process. This allows the same two terminals to be configured for use in sensing process variables and for controlling the process variables as desired. As described herein, load adapter modules can be coupled to the separate outputs and used to direct power to process control elements. The field devices are configured for wireless communication to remote locations. Wireless communication can conform to any suitable technology, such as the WirelessHART® communication protocol compliant with the IEC 62591 Standard.

[0009] The process control industry has many devices that require a load switch on the positive (high) terminal of the power supply to operate. These devices typically have multiple taps that already reference the negative side of the power supply. This can be problematic for wireless DIO controllers, as they can only have a switch located on the negative terminal of the power supply. Switching the load on the positive side of the power supply requires the use of an intervening relay. In this case, the customer needs to mount a secondary enclosure near the field device and control the device using the intervening relay. This results in additional cost, complexity, and a potential secondary point of failure for the customer.

[0010] In one embodiment, the present invention addresses this problem by providing a load adapter module configured to couple to the terminals of a wireless DIO device. The load adapter module is further configured to couple to an external power supply and a process control device. In response to a control signal at the terminals of the DIO device, the load adapter module connects the positive terminal of the external power supply to the process control device. This allows the DIO device to be wired directly to the process control device, eliminating the need for a secondary housing, interface cable, intervening relay, or other additional circuitry that would otherwise need to be implemented by the operator. The load adapter module is transparent to the wireless DIO field device and requires no additional hardware or software to provide functionality. The load adapter module supports the same power range, load requirements, and readback functionality as the wireless DIO device. As described below, the load adapter module is configured to work with both conventional two-terminal DIO channels and three-terminal DIO channels with an internal power supply option. The load adapter module may contain any number of channels. Preferably, the adapter module is designed to maintain hazardous and non-hazardous approval ratings. Preferably, the load adapter module is configured to fit within the housing of an existing DIO field device.

[0011] Figure 1 is a simplified block diagram of an industrial process 10 including a wireless DIO process field device 12 coupled to a process vessel or tank 14. The process vessel can contain a process fluid 8. The wireless DIO field device 12 includes a discrete process interface element 16, which may include a control element if the device is configured to provide discrete control output signals, and may include a process variable sensor if the field device 12 is configured to detect process variables from a discrete process variable sensor. If configured to detect process variables, the field device 12 can wirelessly communicate information about the detected process variables to a remote location 18 via antennas 20 and 22. The remote location 18 may include, for example, a central location such as a control room. An example of a discrete process variable sensor is a switch that changes state when a specific event occurs, such as exceeding a temperature threshold or a level threshold. Another type of discrete process variable sensor provides a series of pulses associated with a countable detected process variable. Examples of such process variable sensors include turbine flowmeters and magnetic flowmeters with pulse outputs. The field device 12 may also be configured to provide a control output. In one example of such a configuration, information is received from a remote location 18, which is used to provide a control output in response. Examples of discrete process control elements controllable by device 12 include motors, actuators, solenoids, resistors, etc. When configured to provide a control output, a load adapter module can be used to switch power to the higher side of the process control element.

[0012] Figures 2A-2C show examples of input / output configurations for a DIO field device. Figure 2A is a simplified block diagram of a field device 12 having a channel 24 configured to receive inputs from individual process variable sensors. In Figure 2A, the process interface element 16 is shown as a two-position (on / off) switch. For example, the interface element 16 may include a level switch that responds to the level of process fluid 8 carried in the tank 14 shown in Figure 1. This switch is connected to the input / output terminal 40 of the field device 12. One terminal 40 is connected to a comparator 42 that also receives a reference voltage. For example, when the switch 16 is closed, a high output is supplied to the microprocessor 44, and when the switch 16 is open, a low output is supplied. The microprocessor 44 receives the output of the comparator 42 and operates according to instructions stored in memory 46. Based on the received input, the microprocessor 44 can communicate wirelessly using the wireless communication circuit 48 and antenna 20.

[0013] Figure 2B shows an alternative configuration of the DIO channel 24 of the field device 12. Channel 24 is coupled to a separate control element. In Figure 2B, the process interface element 16 is shown as a load connected to the voltage source 50. For example, the load 16 may be a relay, a valve actuator, etc. In Figure 2B, the load 16 and the voltage source 50 are connected to the input / output terminal 40 of the field device 12. In the configuration of Figure 2B, instead of using a comparator 42, the field device 12 couples a switch 60 to the voltage source 50 via terminal 40 and connects the load to the negative side of the power supply. The switch 60 operates under the control of the microprocessor 44. Figure 2A shows the device 12 configured to provide an input channel, and Figure 2B shows the device configured to provide an output channel.

[0014] Figure 2C shows another configuration example of the DIO channel 24 of the field device 12. In this configuration, channel 24 is coupled to an external power supply 102 used to power the load 16 by connecting the load 16 to the negative side. This external power supply 102 is a common power supply and is also used to power the field device circuits such as the microprocessor 44, memory 46, and wireless communication circuit 48.

[0015] The configuration of the field device 12 shown in Figures 2B and 2C may pose problems in some process equipment. As discussed herein, certain field devices require operation by connecting them to the positive terminal of a power supply. In the exemplary Figures 2B and 2C, the load can only be connected to the negative terminal of the power supply. As a result, additional components such as relays, wiring, and enclosures may be required to control this type of field device.

[0016] Figure 3 is a more detailed schematic diagram of the field device 12 circuit. In Figure 3, eight channels 24-1 to 24-8 are shown, which operate as either input or output channels as desired. For illustrative purposes only, channel 24-1 will be described in detail. Channel 24-1 has three input / output connection terminals: CH1 EXT, CH1+, and CH1-. For intrinsic safety, protection diodes D100, D101, and D102 are provided. In battery-powered mode (described in more detail below), the CH1+ and CH1- connection terminals are used as both input and output terminals. To close the switch, transistor Q100 is closed using the DO CHANNEL1 input connection terminal via U1000. To operate as an input channel, operational amplifier U100B is coupled to the CH1+ input and supplies output DI CHANNEL1 to the microprocessor 44.

[0017] Channel 24-1 has an additional operating mode that, when connected to an external power supply, can supply power to external components such as the load 16 shown in Figure 2B. In this configuration, the external load is electrically connected between CH1EXT and CH1+. The applied voltage is adjustable by controlling the voltage of the external power supply as desired.

[0018] As shown in Figure 3, two optional power sources are provided in the form of a battery 101 or an external power source 102. The external power source 102 is connected to the external connection terminals EXT+ and EXT-, and similarly, the battery 101 is connected to the battery connection terminals BATT+ and BATT-. A protection element 104 is provided to protect the internal circuitry, and the 8.6 voltage regulator 106 supplies power to the switching regulator 108 via diodes D1, D2, and D3. Power from power source 102 is coupled to the CH1EXT channel via diodes D100~D102, protection element 100, and protection element 104. The 3V output from regulator 108 supplies power to the microcontroller 44 and the wireless communication circuit (radio 48). The microcontroller 44 receives inputs from separate input / output channels 24-1~24-8 and provides outputs to them. Additionally, an arbitrary two-position sliding cover 120 is provided so that only one of the EXT terminals and BATT terminals is always exposed.

[0019] Figure 4A is a simplified electrical schematic showing a load adapter module 200 according to an exemplary embodiment of the present invention. The load adapter module 200 is configured to connect to a 3-terminal wireless DIO device 12 as described in connection with FIG. 3. The module 200 includes a connector for connection to a CH EXT connector that supplies power, and connection terminals for connection to CH+ and CH- connectors. The module 200 also includes three output connection terminals labeled LOAD, +POWER, and -POWER for connection to an external power supply 202 and a field device 16. An operational amplifier U1 is configured to monitor the CH+ output from the device 12 and is powered by connection to the CH EXT power connection terminal. The output from the op-amp U1 is provided to a transistor switch M1, which is configured to switch the power to the load connection to the field device 16 to the high side of the power supply. The module 200 can also be powered by an external power supply 202 via a steering diode D1. Clamp diodes D3 and D4 provide transient protection, and resistors R1 and diode D2 protect the transistor switch M1. Resistor R2 biases the input of the operational amplifier U1. In one configuration where the optional external power supply 202 is not used, when the transistor switch M1 is turned on, power is supplied from the CH EXT connection terminal and the power supply 102 to the field device. Diode D100 supplies power from the power supply 102 to the field device 16 via the transistor switch M1. When the optional external power supply 202 is used, power is supplied to the field device 16 via the steering diode D1 and the transistor switch M1.

[0020] Figure 4B shows a configuration in which the load adapter module 200 is powered by an external power supply 202 and the module 200 is coupled to a 2-terminal wireless DIO field device 12. In this configuration, the field device 12 provides only CH- and CH+ outputs. Power is supplied to both the module 200 and the field device 16 via the steering diode D1.

[0021] FIG. 5 is a perspective view showing the configuration of a load adapter module 200 configured to have two channels. Input connectors CH EXT1, CH+1, and CH-1 for connection to the device 12 are shown. Similar connection terminals for the second channel are hidden in the perspective view of FIG. 5. The adapter module has two output sets of LOAD1, +POWER1, -POWER1, LOAD2, +POWER2, -POWER2. Any number of channels can be implemented in the module 200. The two-channel module 200 is useful in some configurations such as motor-operated valve (MOV) applications. In such a configuration, one channel is used to open the valve and the second channel is used to close the valve.

[0022] FIG. 6 is a perspective view of the front panel 220 of the DIO device 12, and the DIO device 12 includes a number of screw terminals for coupling to input / output connection terminals to the process interface. As shown in FIG. 6, the adapter module 200 is attached to the front panel 220 and screwed to the terminal connection part for the CH EXT, CH+, CH- connection terminals on the front panel 220.

[0023] The adapter module described herein enables more efficient, reliable, and cost-effective installation of DIO field devices for controlling process interfaces requiring high-side drives. The adapter module can be configured to be compatible with any wireless DIO device without modifying the hardware or firmware within the field device. The adapter module supports the existing functionality of the wireless DIO field device while maintaining hazardous and non-hazardous location assessments. The adapter module operates with both 2-wire and 3-wire DIO devices. The module does not affect the diagnostic capabilities of the field device. Separate power supplies can be used for different channels of the adapter module, thereby allowing different voltage levels to be supplied to each channel. The module is scalable and can support any number of channels housed in the field device. Furthermore, the power supply for field device 16 can be at a higher or lower voltage than the power supply 102 for DIO device 12.

[0024] While the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that modifications can be made to the form and details without departing from the spirit and scope of the invention. As shown in the figures, the adapter module can couple different voltage levels to process interface elements. For example, multiple external power supplies can be used. Furthermore, the adapter module can be configured to operate in hazardous and / or non-hazardous environments.

Claims

1. A wireless field device for use in industrial processes, Input / output terminals configured to connect to process interface elements; A discrete input / output channel configured to receive discrete input signals from the process interface element via the input / output terminals when configured as a discrete input channel, and configured to provide discrete outputs to the process interface element via the input / output terminals when configured as a discrete output channel; A wireless communication circuit configured to send and receive information; It is a controller, When the discrete input / output channel is configured as a discrete output channel, a discrete output signal is provided to the process interface element in response to information received by the wireless communication circuit; When the discrete input / output channel is configured as a discrete input channel, a controller is configured to receive a discrete input signal from a process variable sensor and to provide an output in response using the wireless communication circuit; External power input configured to be coupled to an external power supply; and A wireless field device comprising: a load adapter module having a switch coupled to the discrete output signal and the external power input, and configured to connect the process interface element to the higher side of the external power supply in response to the discrete output signal.

2. The wireless field device according to claim 1, wherein the switch includes a transistor.

3. The wireless field device according to claim 1, comprising a comparator configured to couple to the positive and negative channel outputs of the discrete input / output channels and to activate the switch in response thereto.

4. The wireless field device according to claim 1, wherein the discrete input / output channels include the external power input.

5. The wireless field device according to claim 1, comprising a second internal power supply, wherein the load adapter module comprises an external power input configured to be coupled to the second external power supply.

6. The wireless field device according to claim 1, wherein the discrete input / output channels include three connection terminals.

7. The wireless field device according to claim 1, wherein the discrete input / output channels include two connection terminals.

8. The wireless field device according to claim 1, wherein the load adapter module includes a steering diode configured to conduct power from the external power supply to the switch.

9. The wireless field device according to claim 1, wherein the load adapter module includes a steering diode configured to guide power from the external power supply to the circuit of the load adapter module.

10. The wireless field device according to claim 1, wherein the load adapter module is configured to be screwed to the input / output terminals of the discrete input / output channel.

11. The wireless field device according to claim 1, wherein the load adapter module is configured to be housed within the housing of the wireless field device.

12. The wireless field device according to claim 1, wherein the load adapter module includes a screw terminal configured to be electrically connected to the process interface element.

13. The wireless field device according to claim 1, wherein the load adapter module includes a screw terminal configured to be coupled to the external power supply.

14. The wireless field device according to claim 1, wherein the load adapter module includes a second switch and is configured to couple two separate input / output channels.

15. The wireless field device according to claim 1, wherein the load adapter module includes a clamp diode configured to provide transient protection.

16. The wireless field device according to claim 1, comprising a plurality of separate input / output channels.

17. The wireless field device according to claim 16, wherein the load adapter module is coupled to a second discrete output signal and a second external power input having a second switch configured to connect a second process interface element to the second external power supply in response to the second discrete output signal.

18. The wireless field device according to claim 17, wherein the second external power supply provides a voltage different from the voltage provided by the external power supply.

19. The wireless field device according to claim 1, wherein the load adapter module is configured to operate in a hazardous environment.

20. The wireless field device according to claim 1, wherein the load adapter module is configured to operate in a non-hazardous environment.

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