JPH03296198A - Diagnostic method for transmission loop - Google Patents

Abstract

PURPOSE:To shorten the time required for fault diagnosis by connecting a module part to a transmission loop between a transmitter and a receiving instrument and separating the transmission loop on the side of the transmitter and the transmission loop in the side of the receiving instrument from each other. CONSTITUTION:When the transmission loop between the transmitter 1 and receiving instrument 3 is diagnosed, the module part (slave module part 5 and master module part 6) is connected between them, and the transmission loop on the side of the transmitter 1 and the transmission loop on the side of the receiving instrument 3 are separated and diagnosed respectively. Therefore, if one transmission loop becomes abnormal, a transmission loop wire breaking state and the power-off state of the loop can be discriminated automatically. Consequently, the time required for the diagnosis is shortened.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention includes a module part in a transmission loop between a transmitter that detects and transmits the flow rate value of liquid, etc., and a receiving instrument that receives this detection signal. The present invention relates to a method for diagnosing a transmission loop, in which the transmission loop is diagnosed.

[Prior Art] In a receiving instrument that is loop-connected to a transmitter that performs conventional analog data communication and receives signals from the transmitter, burnout low (Low) or high (H
igh) monitors the current flowing through the loop to detect abnormalities in the loop.

Further, in a system in which a transmitter and a receiving instrument that can perform digital data communication are connected in a loop, this loop current is similarly detected to detect whether the transmitting loop is normal or abnormal.

[Problems to be Solved by the Invention] The conventional transmission loop diagnosis method described above has a problem in that it takes a long time to discover the abnormal location because loop abnormalities can only be detected by the burnout low or high method. That is, when an abnormality is detected by burnout low, there is a problem in that it is impossible to distinguish between abnormalities such as process input abnormality 1, transmitter abnormality, loop power supply abnormality, and loop disconnection.

Further, even in the case of a system in which a transmitter capable of digital transmission is connected, there is a problem in that it is not possible to identify whether the transmitter is abnormal or the loop is broken.

In other words, the conventional transmission loop diagnosis method, for both a receiving instrument that receives signals from an analog transmitter and a system that accommodates a digital transmitter, treats a disconnected loop state as being exactly the same as a state in which there is no power to the loop. Therefore, even if an abnormality is detected, it is not possible to identify which part of the abnormality has become abnormal, and therefore there is a problem in that failure diagnosis takes time. This is a method of diagnosing the loop by detecting the current flowing through the loop, so it is possible to detect whether the loop is correct or not only under the conditions of a normal power supply, no disconnection, and a normal transmitter. It is something.

[Means for Solving the Problems] In order to solve the above-mentioned problems, a transmission loop diagnosis method according to the present invention includes a computer, a transmitter, and digital data communication in a transmission loop between a transmitter and a receiving instrument. By connecting the module parts that carry out the test and separating the transmission loop on the transmitter side and the transmission loop on the receiving instrument side, each transmission loop can be diagnosed.

When diagnosing the transmission loop between the transmitter and the receiving instrument, connect the module section between them to separate the transmitter's transmitting loop and the receiving instrument's transmitting loop, and separate the transmitting loop of each transmitting loop. A diagnosis is made. As a result, when the transmission loop becomes abnormal, it is possible to automatically distinguish between the transmission loop disconnection state and the loop no power supply state.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a configuration diagram showing an embodiment of a system to which the transmission loop diagnosis method of the present invention is applied. In the figure, 1 is a transmitter, 2 is a computer, 3 is a receiving meter, and 4 is a receiving meter in which data such as the flow rate value detected by the transmitter 1- is changed analogously to a current value of 4 to 20 mA. 3, E is a power supply for feeding the transmitter 6, and R is a resistor for converting the current value of the 420 transmission line into a voltage input of the receiving instrument. Further, 5 is a lower module section, and 6 is an upper module section.

The lower module section 5 and the upper module section 6 are configured as follows.

That is, 60 is a communication I/F unit that performs data communication with the computer 2, 61 is a CPU that controls the entire upper module unit 6, and 62 is a transmitter 1 and the upper module unit 6.
An A/D converter 63 converts the analog detection signal being sent by the transmitter 1 to the receiving instrument 3 into a digital signal and sends it to the CPU 61 as a hold value when the transmitter 1 performs data communication. 64 is an operational amplifier, and 65 and 66 are input/output buffers. In addition, Ql is a transistor that performs digital data communication with the oscillator 1, Q2 is a transistor that converts a held voltage value into a current value, SWI to SW3 are switches that open and close each loop, and E' is a transistor that communicates with the oscillator 1. Power supply R for powering transmitter 1 during digital data communication
1. R2 is a resistance.

Next, the operation of the transmission loop diagnosis of the system configured as described above will be explained. First, normally only the switch SWI is closed and the other switches are open. and,
The transmitter 1 detects the flow rate of liquid, etc. flowing through pipes installed in factories, etc., converts this detection signal into an analog current value of 4 to 20 mA, and converts this analog signal into a switch S.
It is transmitted to the receiving instrument 3 via WI.

At this time, the voltage drop due to the analog current flowing through the resistor R1 is converted into a digital signal by the A/D converter 62 and sent to the CPU 61. CPU
61, when the voltage value converted to this digital signal is above a certain value, it is considered to be normal, and this result is sent to the communication I.
/F section 60 to the computer 2.

In addition, when the above diagnosis result is determined to be abnormal, C.
The PU61 opens the switch SW1 to cut off the analog current signal from the transmitter, and also opens the switch SW3.
is closed and the digital signal value is sent to the D/A converter 63. This digital signal value is converted into an analog voltage signal value by a D/A converter 63, and is then converted to an analog voltage signal value by an operational amplifier 64. The signal is sent to transistor Q2 via switch SW3.

Thus, this analog voltage signal value is
2, it is converted into an analog current signal value and sent to the 4-20 transmission line 4 in the lower module section 5. At this time, the transmission loop consists of power supply E, transistor Q2. It is formed by resistor R1 and resistor R.

Further, at this time, the voltage drop due to the analog current flowing through the resistor R1 is converted into a digital signal by the A/D converter 62 and sent to the CPU 61. And CPU6
] then compares this digital signal with the value of the digital signal sent to the D/A converter 63, and if the accuracy is within the allowable range, it is determined that the transmission loop including the power supply E on the receiving instrument 3 side is normal. This result is transmitted to the computer 2 via the communication I/F unit 60.

Furthermore, as a result of comparing the values of the two digital signals above, if the accuracy is not within the allowable range and it is determined that the transmitting loop of the receiving instrument 3 (!l!1) is abnormal, the CPU 61 closes the switch SW2. Then, the power supply E is supplied from the upper module section 6 to the transmitter 1 via the switch SW2 and the resistor R2.
It supplies digital data to the oscillator 1 via the transistor Q1 and the output buffers 65 and 66. Then, it is determined whether the transmitter 1 is in a normal or abnormal state depending on whether the result of this data communication is correct or not, and this result is transmitted to the computer 2 via the communication I/F unit 60.

In this way, first, only the switch 5WI- is closed and the output current from the oscillator 1 flowing through the resistor R1 is checked. If this is not above a certain value, the switch SWI is opened and the switch SW3 is closed, and the current value output so as to flow through the resistor R1 and the current value actually flowing through the resistor R1 are
The receiving instrument 30! ! I
Determine whether the transmission loop including the power supply E is correct or not. As a result, it is also possible to determine whether the power source E is correct or not (determine whether or not there is a loop power source). In addition, when determining whether the loop on the transmitter 1 side including transmitter 1 is correct or not, close switch SW2 with switch SWI open, perform digital data communication with transmitter 1, and check whether the loop is correct or not. It was designed to be judged.

[Effects of the Invention] As explained above, in the transmission loop diagnosis method according to the present invention, when diagnosing the transmission loop between the transmitter and the receiving instrument, the module section is connected between them and the transmission loop on the transmitter side is Since the loop and the transmitting loop on the receiving instrument side are separated and each transmitting loop is diagnosed, when a transmitting loop becomes abnormal, it is possible to distinguish between a disconnected state of the transmitting loop and a state of no power to the loop. can be performed automatically, which has the effect of significantly shortening the time required for diagnosis.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of a system to which the transmission loop diagnosis method according to the present invention is applied. 1... Transmitter, 2... Computer, 3...
- Receiving instrument, 4...-4-20 transmission line, 5...-lower module section, 6... upper module section, 60...
...-Communication I/F section, 61...CPU, 62...
・A/D converter, 63-...D/A converter, 64...
... operational amplifier, 65.66 ... input/output buffer,
Ql, Q2...transistor, SWI~SW3...
...Switch, E, E' ...Power supply, R, R1,
R2...Resistance.

Claims (1)

[Claims] A transmitter that has a communication function and detects the flow rate of liquid, etc. flowing through a piped flow path, a receiving instrument that receives a detection signal from the transmitter, and a computer that monitors the status of and sets the transmitter. , connecting a module unit that performs digital data communication with the computer and the transmitter to a transmission loop between the transmitter and the receiving instrument to separate the transmitting loop on the transmitter side and the transmitting loop on the receiving instrument side; A method for diagnosing a transmission loop, characterized in that the transmission loop is diagnosed using the following methods.