JPH05122768A - Process signal receiver - Google Patents

Abstract

PURPOSE:To effectively use the self-diagnostic information and to improve the reliability of a device by holding the information of the self-diagnosed result performed at a smart sensor side at a register. CONSTITUTION:In a sensor 1, a communicating means 13 transmits the process quantity such as temperature, flow quantity and pressure detected by a detecting part 11 to a receiving gauge 2 side by a current signal. At the gauge 2, the current signal corresponding to the process quantity transmitted through a transmission line 3 is converted through a resistance 22, an amplifier 23, and an A/D converter 24 to a digital signal D0 and held at a register means 28. In the same manner, the information of the self-diagnosed result performed by a self-diagnosing means 14 at the sensor 1 side is converted to a digital signal D1, and held at the means 28. The diagnostic information of the action and function of the means 24 of a self-diagnosing means 30 in the gauge 2 and other circuit is held at the means 28 as a digital signal D1. Signals D0, D1 and D2 can be read at the arbitrary timing by a host computer. Thus, the self-diagnostic information can be effectively used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process signal receiver used for industrial measurement, and more specifically, it receives a process signal from a sensor installed in a process and converts this signal into a signal that can be handled by a host computer or the like. And a process signal receiving device.

[0002]

2. Description of the Related Art Recently, a microprocessor or the like is mounted on a transmitter side as a sensor such as a pressure or differential pressure transmitter, an electromagnetic flowmeter, or a thermometer which is installed in a process to detect various process quantities. A so-called smart sensor having so-called intelligent function and communication function has appeared. FIG. 5 is a structural conceptual diagram showing a relationship between the smart sensor and a receiving instrument that receives a process signal from the smart sensor. In the figure, the smart sensor 1 installed in the process has a microprocessor 11, a memory 12, a communication means 13 and the like inside. The detection signal detected by the smart sensor 1 becomes a current signal of 4 to 20 mA, for example, and is transmitted to the receiving instrument 2 side via the two-wire transmission path 3. In addition, various data required on the smart sensor 1 side, for example, calibration data such as zero and span, are sent to the sensor 1 by the receiving instrument 2 side or a communication means such as a handheld terminal that is connected to a transmission line as necessary. The calibration data and other data can be sent from the sensor 1 side to the receiving instrument 2 side as a digital signal. FIG. 6 is a waveform diagram showing a state of a digital signal transmitted from the receiving instrument 2 side to the sensor 1 side or from the sensor 1 side to the receiving instrument 2 side via the two-wire transmission path 3. A digital signal Ds obtained by modulating the current with a minute amplitude is superimposed on a process signal (analog signal) Ip that changes in the range of 4 to 20 mA and is transmitted. Amplitude modulation, frequency modulation, etc. are used for modulation of the digital signal, and the process signal I is generated by superimposing the digital signal.
p is not affected. In the receiving instrument 3, the transmitted process signal Ip and digital signal Ds
Is received as a voltage drop across the resistor Rc. When transmitting a digital signal from the receiving instrument 2 side to the smart sensor 1 side, a current is passed through the resistor Rc according to the digital signal or the voltage of the power source Ec is changed. On either side of the smart sensor 1, the voltage VT between both terminals of the two-wire transmission line 3 changes, so the communication means 13 captures this change and receives the digital signal sent from the receiving instrument 2 side. .. FIG. 7 is a time chart showing a state of a communication procedure performed on the smart sensor 1 side and the receiving instrument 2 side. A command / response system is used in which a command is first sent from the receiving instrument 2 side to the smart sensor 1 side, and the smart sensor 1 always returns a response as a reply to the command. Digital communication by such a command / response method is performed on the smart sensor 1 side, for example, when it is necessary to change the zero point or the range.

[0003]

In the process signal receiving apparatus configured as described above, in the normal state, only the process signal Ip is sent from the smart sensor 1 side, and the receiving instrument 2 side only receives this process signal. Are being received. By the way, the smart sensor 1 has a microprocessor as a main component, and performs various self-diagnosis such as the operation of the microprocessor itself, the memory operation of a memory element, for example, the distortion or characteristic change of the sensor, the measurement environment or the measurement of conditions. It is possible to do. When such self-diagnosis is performed, how to transmit the information of the self-diagnosis result to the receiving instrument side becomes a problem in improving reliability. Further, according to the digital communication shown in FIG. 7, there is a problem in that the self-diagnosis information cannot be taken out unless the smart sensor 1 needs to change the zero point or the range, for example. The present invention is
In view of such a point, it is possible to provide a highly reliable process signal receiving device by making it possible to effectively use the information of the self-diagnosis result performed on the smart sensor side for higher-level control and the like. To aim.

[0004]

SUMMARY OF THE INVENTION The present invention which achieves such an object is provided with a microprocessor-installed sensor installed in a process, a process signal sent from the sensor through a transmission line, and the signal is sent to a computer. In a process signal receiving device composed of a receiving instrument having a function of converting to a signal that can be handled by a self-diagnosis means for self-diagnosing the operation and function of the sensor on the sensor side equipped with the microprocessor, and a self-diagnosis means. Self-diagnosis information transmitting means for transmitting the self-diagnosis information sent as a digital signal, and A / D conversion means for converting the process signal sent through the transmission path into a digital signal on the receiving instrument side; Self-diagnosis that requests the sensor to send diagnostic information and extracts the self-diagnosis information sent from the sensor in response to the request. Information extraction means configured by providing a register means for holding data relating to the self-diagnosis information extracted by the data and diagnostics information extracting means associated with the resulting process signal by the A / D converter.

[0005]

The process signal is always sent from the sensor through the transmission line. Further, the self-diagnosis means performs self-diagnosis of the operation / function of the sensor periodically or as needed. The self-diagnosis information extraction means on the receiving instrument side is
The sensor side is requested to send the self-diagnosis result at regular intervals or as necessary. The sensor receiving this request sends the self-diagnosis result as a digital signal to the receiving instrument side. The self-diagnosis information extracting means on the receiving instrument side extracts the digital signal sent from the sensor side from the process signal, and stores the information in the register means in which the data regarding the process amount is held.

[0006]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the present invention. In the figure, 1 is a sensor equipped with a microprocessor installed in the process. 2 is this sensor 1
Is a receiving instrument connected via a transmission line (in this example, a two-wire transmission line is shown) 3. In the sensor 1, reference numeral 11 is a detection unit that detects process amounts such as temperature, flow rate, pressure, and liquid level. Reference numeral 12 is a signal converting means for inputting the signal from the detecting portion 11 and performing amplification and the like for determining a zero point and a span value. Reference numeral 13 is a general means of the communication means. Is transmitted to the receiving instrument 2 side by a standardized signal such as 4 to 20 mA, or receives a digital signal according to various commands sent to the sensor 1 side via the transmission line 3, and The digital signal in response to the command is returned to the receiving instrument 2 side. The signal conversion unit 12 and the communication unit 13 are wholly or partially configured by using a microprocessor.
Reference numeral 14 is a self-diagnosis unit that self-diagnoses the operation and function of the detection unit 11, the signal conversion unit 12, the communication unit 13, and the like. The communication means 13 includes means for transmitting the self-diagnosis result obtained by the self-diagnosis means 13 as a digital signal to the receiving instrument 2 side.

In the receiving instrument 2, 21 is a DC power supply for moving the sensor 1, 22 is a resistor inserted in the transmission line 3 so as to be in series with the DC power supply 21, and applies a signal to the transmission line or the transmission line. It has a function to take out the signal sent via the. An amplifier 23 inputs a voltage signal generated according to the process signal sent from the sensor 1 side to both ends of the resistor 22, and includes a filter for excluding a digital signal and passing a DC component. Reference numeral 24 is an A / D conversion means for converting the process signal amplified by the amplifier 23 into a digital signal. 25 is a modem, which is a receiving instrument 2
The command signal from the sensor side is modulated into a digital signal and applied to both ends of the resistor 22, or the digital signal sent from the sensor 1 side is separated and taken out from the voltage signals generated at both ends of the resistor 22. , Demodulate it. Two
6 is a switching circuit, 27 is a self-diagnosis information extracting means, which outputs a communication request via the switching circuit 26 and outputs the self-diagnosis result from the digital signal from the sensor 1 side which returns in response to this communication request. Retrieve the information shown. In addition,
Reference numeral 30 is a self-diagnosis means for self-diagnosing the operation and function of each means of the receiving instrument 2.

Reference numeral 28 denotes data D0 relating to the process signal obtained by the A / D conversion means 24, data D1 relating to the self-diagnosis result obtained by the self-diagnosis means 30, and the sensor 1 extracted by the self-diagnosis information extraction means 27. It is a register means for holding data D2 regarding the self-diagnosis result on the side. Reference numeral 29 is a communication means (communication interface) for exchanging data with a host computer or the like, which is connected to the modem 25 via the switching circuit 26. The switching circuit 26 is provided between the modem 25 and the communication means 29, and between the modem 25 and the self-diagnosis information extraction means 2.
It is provided between 7 and is connected to the terminal b side when the host computer communicates, and is connected to the terminal a side when the self-diagnosis information extracting means 27 communicates. Here, the switching circuit 26 and the self-diagnosis information extracting means 2
7, register means 28, communication means 29, self-diagnosis means 3
0 may be realized in part or in whole by a microprocessor. Further, when the receiving instrument is further connected to a host computer, some or all of these circuits or means may be realized in the host computer.

FIG. 2 is a block diagram of essential parts showing a connection relationship of main elements when a host computer is connected to the receiving instrument 2 and digital communication is performed between these and the sensor 1. The modem 25 communicates with the communication means 2 via the switching circuit 26.
The switching circuit 26 is connected to either the 9-side or the self-diagnosis information extracting means 27, and the switching circuit 26 is configured to perform exclusive control of communication requests output from these and execute communication by the modem 25. The various commands modulated and output by the modem 25 are converted into digital signals by passing a current through the resistor 22 and transmitted to the sensor 1 side. In addition, the digital signal from the sensor 1 side is separated and received by the modem 25 from the voltage Vc generated across the resistor 22.

Next, the operation of the apparatus configured as described above will be described separately for handling a process signal (analog signal) and handling a digital signal. (Handling of process signal) In the sensor 1, the communication means 1
3 transmits the process amount such as temperature, flow rate, pressure and liquid level detected by the detection unit 11 to the receiving instrument 2 side as a standardized current signal Ip such as 4 to 20 mA. In the receiving instrument 2, the current signal (process signal) corresponding to the process amount transmitted through the transmission line 3 flows through the resistor 22 and generates the voltage Vc across the resistor 22. The amplifier 23 amplifies only this process signal, and the A / D conversion means 24 converts the average current value of the process signal into a digital signal. The digital signal Do corresponding to the process amount converted here is held in the register means 28. The digital data Do corresponding to the process signal held in the register means 28 can be read by the host computer with an arbitrary towing.

(Handling of Digital Signal) FIG. 3 is a time chart showing an example of the operation when handling a digital signal. Here, the time axis is from the top to the bottom of the paper. In the reception meter 2, the self-diagnosis information extracting means 27 reads the information of the self-diagnosis result of the sensor 1 at the time of T1, for example, to switch the circuit 26.
The communication request REQ1 is issued to and the read command is output. Upon receiving the communication request REQ1, the switching circuit 26 switches the modem 25 to the self-diagnosis information extracting means 27 side, and transmits a read command to the sensor 1 via the modem 25. In the sensor 1 that has received this cond, the communication unit 13 superimposes the information of the self-diagnosis result previously performed by the self-diagnosis unit 14 on the sensor 1 side as a digital signal on the process signal and returns it as a response to the receiving instrument 2 side. .. In the receiving instrument 2, the returned digital signal is received by the modem 25, and at time T2, the self-diagnosis information extracting means 27 extracts the returned self-diagnosis information D2 and stores it in the register means 28. At time T2 when the response is received by the self-diagnosis information extracting means 2, the switching circuit 26 is released. The self-diagnosis information D2 held in the register means 28 is the data D
Like o, it can be read from the upper computer at any timing.

At time T3, the host computer detects the sensor 1
On the other hand, when communication is performed because it is necessary to make adjustments, the transmission request REQ3 is output to the switching circuit 26 via the communication unit 29. Upon receiving the communication request REQ3, the switching circuit 26 connects the modem 25 to the communication means 29 side, and the communication means 29 transmits the adjustment command to the sensor 1 via the modem 25. During this time, for example, at time T4
At this point, even if the self-diagnosis information extracting means 27 issues the communication request REQ4 again for reading the self-diagnosis, the switching circuit 26 is in the state where the communication means 29 is currently using the transmission line 3. The communication request REQ4 to the switching circuit 26 is held as it is as shown by the broken line. When the sensor 1 receives the adjustment command,
According to the adjustment command, for example, the span or zero point is adjusted, and when the adjustment is completed, the response is returned to the receiving instrument 2 side. This response is received by the modem 25 and transferred to the host computer side via the switching circuit 26 and the communication means 29.

The switching circuit 26 is released at time T6 when this response is transferred to the host computer side. When the switching circuit 26 is released, the communication request REQ4 held until then is received, the modem 25 and the self-diagnosis information extracting means 27 are connected, and at time T7, a read command is sent to the sensor 1 via the modem 25. To send. In this way, the switching circuit 26 includes the self-diagnosis information extraction means 27.
The communication request from the communication unit 29 and the communication request from the communication unit 29 are exclusively controlled so that these communication requests can be processed without contradiction. Sensor 1 that received the read command
Returns the self-diagnosis information from the self-diagnosis means 14 as a response as described above, and the information is held in the register means 8 at time T8. Therefore, the self-diagnosis information D2 of the sensor 1 is set at an appropriate time interval (for example, TD).
Then, it is written in the register means 28 and updated. The self-diagnosis means 30 in the receiving instrument 2 carries out self-diagnosis of the operation and function of the A / D conversion means 24 and other circuits as necessary, and holds the diagnosis information D1 in the register means 28. Therefore, from the host computer, the receiving instrument 2
The self-diagnosis information (result) can be read together with other data Do and D2 at any timing.

FIG. 4 is a block diagram of the essential parts of another embodiment of the present invention. In this embodiment, various commands (digital signals) transmitted from the modem 25 in the receiving instrument 2 to the sensor 1 are inserted into the transmission path to the DC power source 2
It is configured such that the voltage is applied to 1 and the voltage value E is changed to transmit. As a method of applying a digital signal to the transmission line, other than this, for example, a current transformer may be inserted in the transmission line, and digital application and extraction may be performed via this. Further, in each of the above embodiments, the receiving instrument 2 is assumed to read the data held in the register means by the upper computer at an arbitrary timing, but the receiving instrument 2 is provided with a microprocessor. In the configuration, the microprocessor may read the register means. Also,
The digital signal of the self-diagnosis information returned from the sensor 1 is supposed to be superimposed on the process signal, but the transmission of the process signal may be temporarily stopped and the digital signal may be returned during that period.

[0015]

As described above in detail, according to the present invention, the information of the self-diagnosis result performed on the sensor side is used as the process signal sent from the sensor side, on the receiving instrument side or the upper computer. Etc. can be handled and the reliability of the device can be improved by effectively utilizing the self-diagnosis information on the sensor side. Further, the communication for obtaining the information on the self-diagnosis result of the sensor can be performed without competing with the command communication for adjusting the sensor, for example.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram of essential parts showing a connection relationship of main elements when a host computer is connected to a receiving instrument and digital communication is performed between these and a sensor.

FIG. 3 is a time chart showing an example of an operation when handling a digital signal.

FIG. 4 is a configuration block diagram of a main part of another embodiment of the present invention.

FIG. 5 is a structural conceptual diagram showing a relationship between a smart sensor and a receiving instrument that receives a process signal from the smart sensor.

FIG. 6 is a waveform diagram showing a state of a digital signal transmitted via a two-wire transmission line.

FIG. 7 is a time chart showing a state of a communication procedure performed on the smart sensor side and the receiving instrument side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sensor 2 reception instrument 11 detection unit 12 signal conversion means 13 communication means 14 self-diagnosis means 21 DC power supply 22 resistance 23 amplifier 24 A / D conversion means 25 modem 26 switching circuit 27 self-diagnosis information extraction means 28 register means 29 communication means

Claims (2)

[Claims] 1. A sensor equipped with a microprocessor installed in a process, and a receiving instrument having a function of receiving a process signal sent from the sensor through a transmission path and converting the signal into a signal that can be processed by a computer. In a process signal receiving device, a self-diagnosis means for self-diagnosing the operation / function of the sensor and a self-diagnosis information transmission for transmitting the self-diagnosis information obtained by the self-diagnosis means as a digital signal to the sensor side equipped with the microprocessor. Means, A / D conversion means for converting a process signal sent via a transmission line into a digital signal, and a request to send self-diagnosis information to the sensor,
Self-diagnosis information extraction means for extracting the self-diagnosis information sent from the sensor side in response to the transmission request, and data related to the process signal obtained by the A / D conversion means and the self-diagnosis information extraction means. A process signal receiving device, comprising: a register means for holding data relating to self-diagnosis information. 2. A communication means for communicating with a host computer to a receiving instrument, and a communication request by performing exclusive control between a communication request from the host computer and a communication request from the self-diagnosis information extracting means via this communication means. The process signal receiving apparatus according to claim 1, further comprising a switching circuit that executes the process.