JPH058905B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a loop check system for self-diagnosis of transmitting and receiving functions in a data transmitting device.

(Prior Art) Generally, as a self-diagnosis of a modem or the like in an off-line state, a manual check method is known in which a self-transmitted signal is returned as a self-received signal.

In this method, the return point is either on the line side of the line interface section or
It is known that the loop check is performed inside the device, and the former case is called a line loop check or AC loop check (AC loop check), and the latter case is called a DC loop check (DC loop check). It is called.

FIG. 4 is an explanatory diagram of the loop location. In the figure, 41 is a CPU section inside the modem, 42 is a transmission logic section that converts transmitted data into electronic data, 43 is a reception logic section that converts received messages into received data, 45, 46
is a DC loop switching gate, 47 is a transmission line interface, 48 is a reception line interface, 49, 50, 51, 52 is an AC loop switching gate, L ₁ , L ₂ are transmission lines, L ₃ ,
_L4 is a receiving line.

According to such a configuration, when a communication failure occurs, for example, if the line loop check result is abnormal and the DC loop check result is normal,
It can be determined that the fault is in the line interface section, and it is possible to determine whether the fault is in the own device or in another device.

FIG. 5 shows an example of a general system configuration in which unidirectional communication and bidirectional communication are mixed and the number of channels accommodated by the main station is large. The channel here refers to a transmitting/receiving line interface and a transmitting/receiving logic unit that communicate with one slave station. In the same figure, 54
is the CPU section of the main station, 55a and 55b are the transmission logic sections of main station channel 1 (CH1) and channel 2 (CH2), 56a and 56b are the reception logic sections of main station CH1 and CH2, and 58a and 58b are the main station CH1 , CH2 reception line interface, 57 is CH2 transmission line interface, 59a, 59b are transmission line interfaces in slave station 1 and slave station 2, 60 is reception line interface in slave station 2, 61a , 61b are reception logic units in slave station 1 and slave station 2, and 62a and 62b are slave station 1 and slave station 2.
The transmission logic in

In this example, if a communication failure occurs,
A manual line loop check or DC loop check is performed to isolate the fault location.

(Problems to be Solved by the Invention) The system shown in Figure 5 above is a subsystem of a crime prevention system, in which a control center is located above the main station and in a remote location, and the main station is operated unmanned. If so, the following problems occurred.

The first problem is that failures can only be isolated manually. This is because even if a criminal intentionally damages a slave station's equipment, the main station and control center will only know that it is a communication failure, so as a safety measure, security guards are dispatched to the slave station first. If it is determined that the system is normal, maintenance personnel will be dispatched to the main station. In other words, communication failures cannot be automatically isolated, resulting in operational waste.

The second problem is that communication failures are generally ignored when no slave stations are connected to the master station's channel, so even if there is a failure in the master station's channel, the slave stations cannot be connected. The problem is that communication failures are noticed for the first time, and it takes time to isolate and recover from the failure.

The third problem is that for channels with control for the purpose of transmitting messages from the master station to control equipment to slave stations, it is impossible to know whether the control system is normal or not until actual control is performed. It is a point. Furthermore, if a control system is to be added to enable control in the future, it will be known whether the control system is normal or not only by performing actual control after the addition. If a communication failure occurs, it will take time to investigate the cause, and as a result, it is assumed that there is a failure in the transmitting logic section or receiving logic section of the relevant channel of the main station. When a situation occurs, a message for control is sent to the slave station, but it is expected that there will be a situation where control is lost.

These first, second, and third problems have received a lot of attention as system issues.

(Means for Solving the Problems) The present invention provides an automatic loop check system applied to data communication between a master station and a slave station, in which the slave station has a means for repeating a fixed message format and a means for repeating a message format. The main station is equipped with means for securing a predetermined time interval from the end to the beginning of the next message, and the main station includes means for detecting the end of the message received from the slave station, and a DC loop that automatically loops at predetermined intervals. or a control means for forming a line loop, and a means for detecting a connection state or an unconnected state with the slave station, and when the control means detects the connection state with the slave station, the control means detects the end of the message from the slave station. DC within said predetermined time interval based on the detection of
A loop or a line loop is formed, and when an unconnected state with a slave station is detected, a DC loop or line loop is formed at regular intervals, and the DC
The configuration is such that a test signal is generated and sent out during a loop or line loop, the test signal is received through the loop, and a match or mismatch with the transmitted test signal is determined.

(Function) In the present invention, for example, in a main station device and a slave station device that perform data transmission, the interval between messages from the slave device to the main station device is set to be longer than a certain period of time, and the main station receives messages from the slave station. Detects the last and automatically
If a CD loop check or line loop check is performed, or if the slave station is waiting for addition,
DC loop check or line loop check can be performed at regular intervals.

Also, the DC loop check or line loop check is not performed while sending the message from the master station device to the slave station device, and after the message transmission is completed, the DC loop check is performed after receiving the last message from the slave station. Alternatively, since a line loop check is performed, various loop checks can be automatically performed without disturbing data communication, whether it is unidirectional or bidirectional communication.

(Example) FIG. 1 shows a first example of the present invention. Inverter 1, AND gates 2, 3, 5, 6, and OR gates 4 and 7 transmit the transmission signal (TXD) output from CPU section 20 to the CPU section when the DC loop output from CPU section 20 reaches the "1" level. 20 received signals (RXD)
This is for wrapping input.

When the DC loop output is "0", the transmission signal (TXD) becomes the transmission signal (SD) as the output of the OR gate 4 and is connected to the input of the modulator 8. Further, the received signal (RD) from the demodulator 9 is output from the OR gate 7 and becomes the RXD input of the CPU section 20.

Transformers 10 and 11 are for impedance matching with a communication line.

Relay contacts 12, 13, 14, 15 are relay 1
6 and 17, the relay contacts 12 and 13 are connected to the relay 16, and the relay contacts 1
4 and 15 are built into the relay 17. In addition,
The state shown in FIG. 1 is a normal state (a state in which communication with the partner station is possible).

When the line loop output of the CPU section 20 becomes "1", the relays 16 and 17 are driven via the transistor array 18, and each relay contact 12, 1
3, 14, and 15 are made in the opposite direction to that shown in FIG. 1, and the output signal of the modulator 8 is input to the demodulator 9, resulting in a line loop state.

FIG. 2 is a diagram for explaining the timing at which a loop check is performed. The following explanation assumes that the device shown in FIG. 1 is the main station. First, the transmission signal from the slave station device is input to the reception signal lines L3 and L4 of the main station device, is demodulated by the demodulator 9 via the transformer 11, becomes an RD signal, and is sent to the CPU through the AND gate 6 and OR gate 7. The received signal (RXD) of the unit 20 is inputted.

When the CPU unit 20 detects the end of the message from the received signal (RXD) signal input through this route,
Set line loop output or DC loop output to “1”
Then, wait for the relay contacts 12, 13, 14, and 15 to become sufficiently stable, and then send the check message to TXD.
Output from output. As a result, the check message is turned back into a reception signal (RXD), and after the reception is completed in the reception processing of the CPU section 20, it is determined whether or not it is the same as the message sent by itself. If it is not, an abnormality occurs. Displays warnings and performs other processing. Furthermore, when the check message is completed, the line loop output and the DC loop output are set to "0" to return to the original state.

Also, when you return to the original state, it would be a problem if the message from the slave station is already in the middle, so make sure to loop-check the interval between the end of the message and the beginning of the next message for the transmission signal from the slave station. The intervals should be as long as possible.

In addition, since the start timing for performing a loop check is after receiving the last message from the slave station device, if the message from the slave station device is made to repeat a certain message format, the loop check can be performed automatically. It happens.

On the other hand, if the slave station device is not connected (so-called waiting for expansion), automatic loop check cannot be performed as it is, so by turning on the separately prepared unconnected setting switch 21, the unconnected This is notified to the CPU unit 20, and a loop check is executed at regular intervals.

In addition, a loop check is not performed while the message is being sent from the master station device to the slave station device, and after the transmission is completed, a loop check is not performed until the end of the message is received from the slave station device. In addition, by not repeating a certain message format for transmission to slave stations, it is possible to operate the system without any problems even in the case of two-way communication.

FIG. 3 is a diagram showing a second embodiment of the present invention, in which there is no modulator as a transmission line interface section. In this case, like the system described above, only the DC loop check is performed.

(Effects of the Invention) As described above using the embodiments, according to the present invention, within a predetermined time interval from the end of the message from the slave station to the beginning of the next message, the last message of the message is detected. Since DC loops or line loops are formed based on the data, automatic loop checks can be performed without disrupting data communication, making it possible to automate the identification of the cause of communication failures and reducing operational waste. Furthermore, in the relationship between the main station device and the slave station device, it becomes possible to detect a failure in the device itself before actual control is performed, and the unit can be maintained and replaced before actual control is required. Furthermore, the main station has the advantage of being able to detect its own failures before adding slave stations, improving maintainability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG.
The figure is a diagram for explaining the execution timing of the loop check in the first embodiment, and FIG.
FIG. 4 is a diagram for explaining a loop location in the prior art, and FIG. 5 is a diagram for explaining a general system in the prior art. 1...Inverter, 2, 3, 5, 6...AND
Gate, 4, 7...OR gate, 8...Modulator,
9... Demodulator, 10, 11... Transformer, 12,
13, 14, 15... Relay contact, 16, 17...
...Relay, 18...Transistor array, 20...
...CPU section, 21...Disconnection confirmation switch.

Claims (1)

[Claims] 1. In an automatic loop check method applied to data communication between a master station and a slave station, the slave station has means for repeating a certain message format;
The main station is equipped with a means for ensuring a predetermined time interval from the end of one message to the beginning of the next message, and the main station is equipped with a means for detecting the end of the message received from the slave station, and a means for automatically detecting the end of the message received from the slave station. control means for forming a DC loop or a line loop in the main station, and means for detecting connection or disconnection state with the slave station, and when the control means of the master station detects the connection state with the slave station, A DC loop or line loop is formed within the predetermined time interval based on the last detection of the message from the station, or a DC loop or line loop is formed at regular intervals when a disconnection state with the slave station is detected. an automatic loop, which generates and transmits a test signal during the DC loop or line loop, receives the test signal through the loop, and determines whether it matches or does not match the transmitted test signal. Check method.