JP2012203447A - Input output device having hart communication function - Google Patents

Abstract

To facilitate maintenance when a failure occurs.
A HART communication signal generated by superimposing an AC signal expressed by converting a digital signal into a frequency signal of 1200 Hz and 2200 Hz on a DC signal of 4 to 20 mA is wired from a HART communication compatible device 10. 20, the HART communication unit 111 that separates the received HART communication signal into a 4 to 20 mA DC signal and an AC signal, and the 4 to 20 mA DC signal and the AC signal separated by the HART communication unit 111. And a diagnosis unit 112 for diagnosing the state from the own HART-IO unit 11 to the HART communication-compatible device 10.
[Selection] Figure 2

Description

  The present invention relates to an input / output device having a HART communication function.

  At the site where production processes are managed, various field devices (for example, sensors and valves) having a transmission function are installed in the plant, and various production processes are managed by incorporating signals transmitted from the field devices into the system. ing. As a system for managing a production process, for example, there is a system that controls the opening degree of a valve based on a flow rate, temperature, pressure, or the like acquired from a sensor. In recent years, as a field device connected to such a process management system, a device equipped with a HART (Highway Addressable Remote Transducer) communication function (hereinafter referred to as “HART communication compatible device”) has been adopted. A HART communication-compatible device generates a signal generated by superimposing an AC signal represented by converting a digital signal into a frequency signal of 1200 Hz and 2200 Hz on a DC signal of 4 to 20 mA indicating a measured value or a control value (hereinafter, referred to as a HART communication compatible device). , “HART communication signal”). That is, the HART communication-compatible device can exchange various information in addition to the measurement value and the control value. The following Patent Document 1 and Patent Document 2 disclose systems using HART communication-compatible devices.

JP 2003-186503 A Japanese Patent No. 4129715

  In the above-described system for managing production processes, when a failure occurs between a HART communication-compatible device and a communication module on the higher side, there is no means for identifying the content of the failure and the location where the failure occurred. Time is required for maintenance when it occurs.

  The present invention has been made to solve the above-described problems caused by the prior art, and an object thereof is to provide an input / output device having a HART communication function that can facilitate maintenance when a failure occurs. .

  An input / output device having a HART communication function according to the present invention receives a HART communication signal generated by superimposing a second signal on a first signal from an external device via a wire, and receives the received HART communication signal. HART communication unit that separates the first signal and the second signal, and the state from the own device to the external device based on the first signal and the second signal separated by the HART communication unit A diagnosis unit for diagnosis.

  By adopting such a configuration, the state from the own device to the external device is diagnosed based on the first signal and the second signal transmitted from the external device via the wiring and separated by the HART communication unit. Is possible.

  The diagnosis unit may diagnose the state of the external device and the wiring by comparing the value of the first signal and the value of the second signal. The diagnosis unit may diagnose the state of the wiring by specifying whether the state of the wiring corresponds to normal or abnormal wiring.

  The diagnostic unit transmits a digital signal corresponding to the result of the diagnosis to a device on the monitoring system side that monitors the own device, and a digital signal corresponding to the second signal is transmitted to the monitoring system side that monitors the own device. It is good also as transmitting to addressed equipment.

  The first signal may be a DC signal of 4 to 20 mA, and the second signal may be an AC signal represented by a frequency signal obtained by converting a digital signal.

  According to the present invention, an input / output device having a HART communication function capable of facilitating maintenance when a failure occurs can be provided.

It is a figure which illustrates the structure of the process management system which employ | adopted the input / output device which has a HART communication function in embodiment. It is a figure which illustrates the function structure of the input / output device which has a HART communication function in this embodiment. It is a figure for demonstrating the specific example of a diagnostic result.

  Embodiments according to the present invention will be described below with reference to the drawings. However, the embodiment described below is merely an example, and does not exclude application of various modifications and techniques not explicitly described below. That is, the present invention can be implemented with various modifications without departing from the spirit of the present invention.

  First, the configuration of a process management system that employs an input / output device having a HART communication function (hereinafter referred to as “HART-IO unit”) in the embodiment will be described with reference to FIG. As shown in FIG. 1, the process management system 1 includes HART communication compatible devices 10i and 10o, HART-IO units 11i and 11o, field devices 12i and 12o, IO units 13i and 13o, a HUB 14, and device monitoring. A unit 15, a controller 17, and a driving operation unit 19.

  The controller 17 and the operation unit 19 provided on the upper side of the HART-IO units 11i and 11o and the IO units 13i and 13o constitute a control system that controls the process. On the other hand, the HUB 14 and the device monitoring unit 15 provided on the upper side of the HART-IO units 11i and 11o constitute a monitoring system for monitoring the status of the HART communication-compatible devices 10i and 10o.

  The HART-IO units 11i and 11o and the IO units 13i and 13o constituting the control system and the controller 17 are connected by a low-speed communication bus 18, for example. The HART-IO units 11i, 11o and the HUB 14 constituting the monitoring system are connected by an Ethernet (registered trademark) standard communication cable 16.

  As the HART communication-compatible device 10i and the field device 12i, for example, various sensors such as a flow rate sensor, a pressure sensor, and a temperature sensor can be used. As the HART communication-compatible device 10o and the field device 12o, for example, a valve such as a flow rate control valve or a pressure control valve or an actuator such as a pump or a fan can be used.

  The HART communication-compatible devices 10i and 10o are field devices equipped with a HART communication function, and input / output a HART communication signal. The HART communication signal is a signal generated by superimposing an AC signal expressed by converting a digital signal into a frequency signal of 1200 Hz and 2200 Hz on a DC signal of 4 to 20 mA.

  The DC signal is a signal indicating the value of one variable set for each HART communication-compatible device or field device. Examples of variable values include measured values such as flow rate, pressure, and temperature, and control values such as valve opening. The digital signal is, for example, a signal indicating various data that can be collected in the HART communication-compatible device. As various data, for example, process information in a HART communication-compatible device and hardware failure information incorporated in the HART communication-compatible device are applicable. In addition, it is good also as including the measured value and control value of a HART communication corresponding | compatible apparatus in various data.

  The HART communication-compatible devices 10i and 10o generate the HART communication signal as follows, for example. First, the HART communication-compatible devices 10i and 10o convert a digital signal represented by 1 and 0 into an AC signal represented by a 1200 Hz frequency signal and a 2200 Hz frequency signal. Subsequently, the HART communication-compatible devices 10i and 10o superimpose the converted AC signal on a 4 to 20 mA DC signal indicating a measurement value, a control value, and the like. Thereby, a HART communication signal is generated.

  The HART-IO units 11i and 11o send and receive HART communication signals to and from the HART communication-compatible devices 10i and 10o, and send and receive 4 to 20 mA DC signals or digital signals to and from the control system or monitoring system. Output device. For example, the HART-IO units 11i and 11o generate a 4 to 20 mA DC signal and a digital signal from the HART communication signal as follows. First, the HART-IO units 11i and 11o separate the received HART communication signal into an AC signal represented by a 1200 Hz frequency signal and a 2200 Hz frequency signal and a 4 to 20 mA DC signal. Subsequently, the HART-IO units 11i and 11o convert the separated AC signals into digital signals.

  The device monitoring unit 15 receives the digital signal output from the HART-IO units 11 i and 11 o via the HUB 14. Based on the received digital signal, the device monitoring unit 15 performs the process execution status in the HART communication compatible device, the failure status of the hardware incorporated in the HART communication compatible device, and the maintenance and repair of the HART communication compatible device. Diagnose the necessary time. The device monitoring unit 15 displays the diagnosis result and the like on the monitor. Thereby, the operator can monitor the HART communication-compatible device.

  The controller 17 controls the implementation state of the production process by controlling the HART communication-compatible devices 10i, 10o and the field devices 12i, 12o. Specifically, for example, the controller 17 controls the HART communication-compatible device 10o or the field device 12o based on the measured values such as the flow rate and pressure acquired from the HART communication-compatible device 10i or the field device 12i, thereby Adjust the opening.

  The driving operation unit 19 displays the operation contents of the HART communication-compatible device 10 i and the field device 12 i on the monitor based on the 4 to 20 mA DC signal received by the controller 17. As a result, the operator can grasp the operation details of the HART communication-compatible device 10i and the field device 12i. The driving operation unit 19 operates the operating state of the HART communication-compatible devices 10i, 10o or the field devices 12i, 12o in accordance with an operation instruction from the operator. The operation content in the operating state corresponds to, for example, device start-up operation or stop operation.

  With reference to FIG. 2, the functional configuration of the HART-IO unit 11 in the present embodiment will be described. As shown in FIG. 2, the HART-IO unit 11 includes a HART communication unit 111 and a diagnosis unit 112. The HART-IO unit 11 may be either the HART-IO unit 11i or the HART-IO unit 11o.

  The HART communication unit 111 separates the HART communication signal received from the HART communication-compatible device 10 into a 4 to 20 mA DC signal and an AC signal, and transmits them to the diagnosis unit 112. The HART communication unit 111 and the diagnosis unit 112 transmit and receive a 4 to 20 mA DC signal via the first signal line S1, and transmit and receive an AC signal via the second signal line S2.

  The diagnosis unit 112 is physically configured by, for example, a CPU and its peripheral devices. The diagnosis unit 112 diagnoses the state of the wiring 20 and the HART communication-compatible device 10 arranged on the lower side of the HART-IO unit 11 based on the DC signal and the AC signal received from the HART communication unit 111, and diagnoses The result is transmitted to the device monitoring unit 15. As the lower-level state, for example, a wiring deterioration state, a disconnection state, an abnormal state of a HART communication-compatible device, or the like is applicable.

  Here, for example, when the insulation or the like of the wiring 20 is deteriorated and a leak occurs, or when the wiring 20 is disconnected and the DC impedance is increased, the DC signal of 4 to 20 mA is greatly disturbed. On the other hand, the AC signal composed of the high frequency signal is communicated with almost no disturbance. Therefore, it is possible to determine the deterioration state of the wiring 20 by comparing the state of the DC signal of 4 to 20 mA with the state of the AC signal.

  A specific example of determining the deterioration state of the wiring 20 will be described with reference to FIG. Here, the value of the DC signal of 4 to 20 mA shown in FIG. 3 is represented by 0 to 100% corresponding to the value of 4 to 20 mA that can be taken as a normal value. That is, when the DC signal is 4 mA, it is represented by 0%, and when it is 20 mA, it is represented by 100%. Similarly, the value of the AC signal is represented by 0 to 100% corresponding to the range of values that can be taken as normal values of the AC signal.

  In addition, it is assumed that the HART communication-compatible device 10 used in this description has an assumed error range of −0.1% to 0.1% for a DC signal of 4 to 20 mA. Further, it is assumed that 63% is set in advance as the value of the AC signal in the HART communication-compatible device 10.

  As shown in the first row of FIG. 3, the value of the 4-20 mA DC signal received via the first signal line S1 is 63.1%, and the AC signal received via the second signal line S2. When the value of 63 is 63%, the diagnosis unit 112 determines that the wiring 20 is normal. In this case, the value of the AC signal is the same as the set value, whereas the value of the DC signal is 0.1% higher than the set value, that is, the value of the AC signal. However, since this 0.1% error is within the range of the assumed error, the diagnosis unit 112 determines that the wiring 20 is normal.

  As shown in the second stage of FIG. 3, the value of the 4-20 mA DC signal received via the first signal line S1 is 58%, and the AC signal received via the second signal line S2 is 58%. When the value is 63%, the diagnosis unit 112 determines that the wiring is abnormal. In this case, the value of the AC signal is the same as the set value, whereas the value of the DC signal is 5% lower than the set value, that is, the value of the AC signal. Since this 5% error is outside the range of the assumed error, the diagnosis unit 112 determines that the wiring 20 is abnormal. Such a situation is a unique phenomenon that appears when the wiring 20 is deteriorated.

  Thus, the deterioration state of the wiring 20 can be appropriately determined according to the difference between the value of the DC signal and the value of the AC signal when the value of the AC signal is the same as the set value. Specifically, when the value of the AC signal is equal to the set value, the wiring deteriorates as the difference between the value of the DC signal and the value of the AC signal increases beyond the range of the assumed error. Can be determined.

  Further, by monitoring the value of the DC signal of 4 to 20 mA, it is possible to determine not only the deterioration state of the wiring 20 but also the disconnection state of the wiring 20 and the abnormal state of the HART communication-compatible device 10. For example, as shown in the third row of FIG. 3, when the value of the 4 to 20 mA DC signal received via the first signal line S1 is “−25%”, that is, 0 mA, the wiring 20 is disconnected. Can be determined. Furthermore, as shown in the fourth row of FIG. 3, when the value of the 4-20 mA DC signal received via the first signal line S1 is outside the range of 0-100%, the HART communication compatible device 10 can be determined to have an abnormality such as a failure. In addition, an AC signal is not received when there is an abnormality in the disconnection or the HART communication-compatible device 10.

  The diagnostic unit 112 shown in FIG. 2 converts an AC signal represented by a 1200 Hz frequency signal and a 2200 Hz frequency signal into a digital signal represented by 1 and 0, and then transmits the digital signal to the device monitoring unit 15. And a function of transmitting a DC signal of 4 to 20 mA to the controller 17. Note that these functions may be separated from the functions of the diagnosis unit 112 and provided in the HART-IO unit 11 as functions different from the diagnosis unit 112.

  As described above, according to the HART-IO unit in the present embodiment, the 4-20 mA DC signal and the AC signal transmitted from the HART communication-compatible device 10 via the wiring 20 and separated by the HART communication unit 111 are converted to the HART-IO unit. Based on this, it is possible to diagnose the deterioration state or disconnection state of the wiring 20 and the abnormal state of the HART communication-compatible device 10. Therefore, when a failure occurs, it is possible to specify the content of the failure and the location where the failure has occurred, so that maintenance at the time of the failure can be facilitated.

  In the above-described embodiment, the case where the diagnostic unit 112 is configured by one CPU has been described. However, the diagnostic unit may be configured by two CPUs. In this case, for example, the first diagnostic unit corresponding to the first CPU and the second diagnostic unit corresponding to the second CPU are provided, and the 4-20 mA separated by the HART communication unit 111 is provided. The DC signal is received by the first diagnosis unit, and the AC signal separated by the HART communication unit 111 is received by the second diagnosis unit. Each time the first diagnosis unit and the second diagnosis unit receive a signal from the HART communication unit 111, the first diagnosis unit and the second diagnosis unit mutually transmit a reception notification indicating that the signal has been received. As a result, when one diagnostic unit receives a signal from the HART communication unit 111 and cannot receive a reception notification from the other diagnostic unit, the other diagnostic unit, that is, the other CPU has a failure or the like. It is possible to determine that there is an abnormality. This makes it possible to diagnose the state from the own HART-IO unit 11 to the HART communication-compatible device 10 based on the 4-20 mA DC signal and AC signal separated by the HART communication unit 111.

  In the above-described embodiment, the HART communication-compatible device 10 may transmit information unique to the device itself to the HART-IO unit 11 as diagnostic information. As the diagnostic information, for example, an upper limit value of a change rate of a value transmitted by the own device to the HART-IO unit 11 corresponds. Thereby, since the HART-IO unit 11 can determine the deterioration state of the wiring and the abnormal state of the device according to the communication quality that differs for each HART communication-compatible device 10, the determination accuracy by the diagnosis unit can be improved. It becomes possible.

  DESCRIPTION OF SYMBOLS 1 ... Process management system, 10 ... Communication corresponding | compatible apparatus, 11 ... HART-IO unit, 12 ... Field device, 13 ... IO unit, 14 ... HUB, 15 ... Equipment monitoring part, 16 ... Communication cable, 17 ... Controller, 18 ... Communication bus, 19 ... driving operation part, 20 ... wiring, 111 ... HART communication part, 112 ... diagnostic part.

Claims (6)

A HART communication signal generated by superimposing the second signal on the first signal is received from an external device via a wiring, and the received HART communication signal is separated into the first signal and the second signal. A communication department;
Based on the first signal and the second signal separated by the HART communication unit, a diagnostic unit for diagnosing a state from the own device to the external device;
An input / output device having a HART communication function. The diagnosis unit diagnoses the state of the external device and the wiring by comparing the value of the first signal and the value of the second signal.
The input / output device having a HART communication function according to claim 1. The diagnosis unit diagnoses the state of the wiring by specifying whether the state of the wiring corresponds to normal or abnormal wiring,
The input / output device having a HART communication function according to claim 2. The diagnostic unit transmits a digital signal corresponding to the result of the diagnosis to a device on the monitoring system side that monitors the own device,
The input / output device having a HART communication function according to any one of claims 1 to 3. The diagnostic unit transmits a digital signal corresponding to the second signal to a device on the monitoring system side that monitors the own device,
5. An input / output device having a HART communication function according to claim 1.   The first signal is a DC signal of 4 to 20 mA, and the second signal is an AC signal represented by a frequency signal obtained by converting a digital signal. An input / output device having the described HART communication function.

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