JPS59200934A - Measuring method of temperature measuring resistor - Google Patents

Abstract

PURPOSE:To improve the quality of temperature measuring value data and to detect and restore a fault quickly by deciding the abnormality of a process I/O device when a measuring value of a testing reference resistor exceeds an allowable range. CONSTITUTION:A central pcocessor 1 selects a relay C at first, so that contacts c1-c3 of the relay C are actuated and the testing reference resistor 29 is connected. If the measuring value of the testing reference resistor 29 exceeds the allowable error, the central processor 1 decides the generation of a fault in the process I/O device 2. At that time, all temperature measuring values from the temperature measuring resistor 3 are cancelled and the abnormality of the measuring value of the testing reference resistor 29 is informed to the operator.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to temperature measurement using a process input/output device that controls the interface between a resistance temperature detector and a central processing unit as well as an interface between the resistance temperature detector and the central processing unit in a building management system or the like. It is related to the measurement method.

(Background Art) Figure 1 shows a conventional temperature measurement system using a resistance temperature detector, a process input/output device, and a central processing unit. In the figure, 1 is the central processing unit of an electronic computer, and 2 is the process input/output The device 3 is a resistance temperature sensor.

The process input/output device 2 includes a signal input terminal board 21.degree. relay multiplexer 22. Resistance/voltage converter path.

Gate circuit for each analog/digital converter 25. The latch circuit is the decoder circuit 27. Consists of control circuitry.

The relay multiplexer 22 includes relays A, B, and Sv-
A contacts a,, a2. a3. Contact b1 of relay B.
b2゜b3 has also become.

In the temperature measurement system, when the process input/output device 2 is selected by the central processing unit 1, the control circuit is activated;
The relay designation data of the relay multiplexer 22 sent from the central processing unit 1 is set in the latch circuit 26, and the relay designation data of the relay multiplexer 22 is sent via the decoder circuit 27.
2 is selected and connected to the resistance temperature detector 3. For example, if relay A is selected, contacts a, C2, C of relay A
3 is activated and connected to the resistance temperature sensor 31.

The resistance value of the resistance temperature detector 3 is converted to a voltage value by a resistance/voltage converter 23 via a signal input terminal board 21 and a relay multiplexer 22, digitized by an analog/digital converter 24, and sent to a gate circuit 5. The data is sent to the central processing unit 1 and operated to be recognized.

However, even if a fault occurs in the process input/output device 2 and an entirely incorrect temperature measurement value is sent to the central processing unit 1, the central processing unit 1 will be notified that the measured value is incorrect data. If there is no other way, it will take time for the operator to realize that the measured value is incorrect, and
During that time, there was a drawback that erroneous measured values were adopted.

Furthermore, even if the operator notices an erroneous measurement value, he or she cannot immediately determine whether all the temperature measurement values are erroneous data or whether only the temperature measurement value for a specific resistance temperature sensor is erroneous data, and therefore, the operator cannot determine the location of the fault. The disadvantage is that it takes time to limit the situation, and recovery is delayed.

(Problems to be solved by the invention) In order to solve all of these drawbacks, the purpose of the present invention is to incorporate a reference resistance for verification into the process input/output device, and to confirm normal operation using the reference resistance for verification when measuring temperature. If it is an abnormal value, it is determined that a failure has occurred, all temperature measurement values at that time are discarded, and the operator is notified. This improves the quality of temperature measurement data and enables early detection and recovery of failures. Details are below. Explain.

(Structure and operation of the invention) FIG. 2 shows an embodiment of the present invention, and the same components as in FIG. 1 are denoted by the same reference numerals. i.e. 1
2 is a central processing unit of the computer, 2 is a process input/output device, 3 is a resistance temperature sensor, and the signal input terminal board 21. Relay multiplexer 22. Relays A, B, C, contacts of relay A"l C2+ C3+ contacts of relay B, ', b2
．． b3. Relay C contact CI I C2hC3 + resistance/voltage converter. Analog/digital converter 24. Gate circuit 5. Latch circuit 26. Decoder circuit 27. It is composed of a control circuit section and a reference resistance for verification 29.

Next, the operation will be explained. When performing temperature measurement, when the process input/output device 2 is selected by the central processing unit 1, the control circuit is activated, and the latch circuit 26 is connected to the central processing unit 1.
The relay designation data sent from the relay multiplexer 22 is set.

First, relay C is designated as data to select the reference resistance for verification 29, and relay C is selected at the relay multiplexer ρ via the decoder circuit 27, and the contacts of relay C, CII C2+C3, are activated, and the reference resistance for verification is selected. It was connected to 29 and ended.

The resistance value of the verification reference resistor 29 is converted to a voltage value across the resistance/voltage converter via the relay multiplexer 22,
The signal is digitized by the analog/digital converter 24, sent to the gate circuit 5, and recognized by the central processing unit 1.

Next, when the process input/output device 2 is selected by the central processing unit 1 for temperature measurement, the control circuit is activated, and the relay multiplexer 220 designation data sent from the central processing unit 1 is set in the latch circuit 26. .

Relay A is specified as data to select the resistance temperature sensor 31, relay A is selected in the relay multiplexer 22 via the decoder circuit 27, and the contacts of relay A, a
,, C2 and C3 are activated and connected to the resistance temperature detector 31.

The resistance value of the resistance temperature sensor 31 is determined by the relay multiplexer 22.
is converted into a voltage value by a resistance/voltage converter, digitized by an analog/digital converter, sent to the gate circuit 5, and recognized by the central processing unit 1.

Next, relay B is specified as data in the same way, relay B is selected, and the contact of relay B, bl+ 1) 2+b
3 is activated, connected to the resistance temperature detector 32, and the resistance temperature detector 3 is activated.
The resistance value 2 is converted into a voltage value and a digital value, and recognized by the central processing unit 2.

Here, if the measured value of the verification reference resistance 29 is not within the allowable error, the central processing unit 1 determines that a failure has occurred in the process input/output device 2 and that an incorrect temperature measurement value has been sent overall. All temperature measurements from the resistance temperature sensor 3 at that point in time are discarded, and the operator is notified that the measurement value of the verification reference resistance 29 is abnormal. As explained above, in the first embodiment, the process input/output device 2 has a built-in reference resistance for verification, and a fault in the process input/output device may result in an overall incorrect temperature measurement value. Since the central processing unit can be notified that the measured value is incorrect even if the measured value is sent to the This has the advantage of shortening the failure recovery time because the amount of abnormality notification can be reported and the location of the failure can be limited.

In addition, if the operator notices an abnormality in the measured value,
There is an advantage that the failure location can be limited to an individual failure mainly caused by the resistance temperature sensor corresponding to the measured value.

In the first embodiment, the resistance temperature detector measurement method has been described which corresponds to two resistance temperature detectors, but it may correspond to one or three or more.

In addition, although the reference resistance for verification was measured once before measuring the resistance temperature sensor, it is also possible to The measurement may be performed after the body is measured, and the reference resistance for verification may be measured two or more times. 9Also, when first measuring the standard resistance for verification, if the measured value is outside the allowable range, immediately consider it as an abnormality, and stop measuring the resistance temperature sensor and measure the standard resistance for verification again. good.

(Effects of the Invention) The present invention has a built-in reference resistance for verification in the process input/output device, so it is possible to discard erroneous temperature measurement data, and it is also possible to notify the operator of abnormalities and abnormalities in a limited manner. If applied to systems such as management systems that operate 24 hours a day and use temperature measurements to control air conditioning, it would be beneficial to prevent incorrect control and save energy and labor.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional temperature measurement system, and FIG. 2 is a block diagram of a temperature measurement system according to the present invention. ■...Central processing unit, 2...Process input/output device,
3...Resistance temperature sensor, 21...Ura input terminal board, 22
...Relay multi-solexer, η...Resistance/voltage converter, Jun...Analog/deftal converter, 5...Gate circuit, 26...Latch circuit, 27...Decoder circuit,・Control circuit, 29... Standard resistance for verification, A, B
, C...Relay, al. a2+ a3. b, + ')2 + b3+ c,
I c2. c3°°° relay contact, 31, 32・
...Resistance temperature sensor. Patent applicant Oki Electric Industry Co., Ltd. Patent application agent Megumi Yamamoto −

Claims (1)

[Claims] In a temperature measurement method that uses a resistance thermometer as a temperature sensor and sends the measurement result to a central processing unit via a process input/output device, the process input/output device has a built-in reference resistance for verification, and when measuring temperature, , the process input/output device is determined to be abnormal if the temperature is measured after confirming normal operation using the standard resistance for verification and the measured value of the standard resistance for verification is outside the allowable range. A resistance temperature detector measurement method.