JPS59158144A - Data transmission system - Google Patents

Abstract

PURPOSE:To reuse a recovered slave station speedily and to repair a fault point speedily by allowing a master station to check the fault and recovery of a slave station at a specific period independently of the timing of the requesting of data transmission. CONSTITUTION:A CPU1 outputs data showing that there are slave stations RST41-RST4n to the master station MST2 and starts inquiring their states of the RSTs. This inquiry is performed periodically, and if there is abnormality in an answer from an RST, that is reported to the CPU1. Once the abnormality is detected, the inquiry is interrupted and the MST2 detects its recovery in a longer period for the recovery detectionof the RST. When the recovery of the RST is detected, that is reported to the CPU1, which then transmits and receives data to and from this RST. The MST2 performs self-returning operation in addition to said inquiry to test its transmitting and receiving circuit 6.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a multi-drop data transmission device.
In particular, the present invention relates to a data transmission system suitable for detecting failures and temporary tightening of remote stations.

[Technical background of the invention]

FIG. 1 is a block diagram showing an example of a conventional data transmission device. A manutar station 7 (MST) 2 is connected to the central processing unit (CPU) 1, and a plurality of remote stations (R8
T) 41 to 4n are connected.

In a conventional data transmission device with such a configuration, R
Abnormalities in 8T41 to 4n are checked when a data transmission request is issued from the CPU to R8T, and if an abnormality is detected at that time, the CPU
R8T where an abnormality has occurred since the software of I
Requests for data transmission were prohibited.

[Problems with background technology]

For this reason, if a temporary gs'r failure automatically recovers, or if maintenance personnel repair the faulty R8T and restore it to normal, the operator will issue an error message to the CPU software. There was a drawback that the R8T could not be reused unless the R8T was notified of its return to normal. In addition, if MST2 fails, it is detected as a failure in R8T from the CPU1 side, so it is difficult to tell whether it is an abnormality in R8T or MST, and it is difficult to immediately identify where the failure is, so it is difficult to repair. This method has the drawback of being time consuming and deteriorating the operating rate of the equipment.

[Purpose of the invention]

The purpose of the present invention is to address the above-mentioned drawbacks and provide a data transmission system that can quickly reuse returned remote stations and quickly repair any malfunctions or openings. There is a particular thing.

[Summary of the invention]

The present invention provides a data transmission device in which a plurality of remote stations are connected to a transmission path exiting from a master station connected to a central processing unit, which is independent of the timing of data transmission from the central processing unit to the remote stations. The above objective is achieved by adopting a method in which the master station checks the failure and recovery of the remote station at a predetermined period, and also checks its own failure and recovery, and notifies the central processing unit of these results. .

[Embodiments of the invention]

An embodiment of the data transmission system of the present invention will be described below with reference to the drawings, using the same reference numerals for the same parts as in the conventional example. FIG. 2 is a configuration diagram showing an embodiment of a data transmission device to which the data transmission method of the present invention is applied.

Central processing unit (CPU) IK master station (M
ST) 2 is connected, and n remote stations (asT) 41 to 4 are connected to the transmission line 3 exiting from this MST 2.
n is connected. The MST 2 includes a microprocessor 5 and a transmitter/receiver circuit 6 connected to the microprocessor 5. The transmitter/receiver circuit 6 is connected to the transmission line 3. Remote station 41-4
Each of n has a microprocessor 7 and a transmitter/receiver circuit 8 connected to the microprocessor 7, and the transmitter/receiver circuit 8 is connected to the transmission line 3.

FIG. 3 is a block diagram showing details of the transmitting/receiving circuit 6 of the MST 2. As shown in FIG. The signal from the microprocessor 5 enters a modulation circuit 9 where it is modulated. The modulated signal is input to the transmission driver 10, and sent to the transmission line 3 by the transmission driver 10. Also, the signal from transmission line 3 is sent to receiver 1.
The received signal is input to the demodulation circuit 13 via the selector 12, and the signal modulated by the demodulation circuit 13 is taken into the microprocessor 5.

Note that the modulation signal output from the modulation circuit 9 is sent to the selector 1.
2 and is immediately returned to the demodulation circuit 13. That is, by switching the selector 12,
The demodulation circuit 13 is configured to receive either a signal from the receiver 11 or a signal from the modulation circuit 9. Therefore, the signal from the modulation circuit 9 can be immediately looped back and input to the demodulation circuit 13 without passing through the transmission line 3.

Next, the operation of this embodiment will be explained. First, to start the operation of the entire system, the CPU 1 sends an R8T4. Data indicating the presence or absence of ~4n is output. This data indicates whether or not R8T corresponding to that address exists (not shown, but Garter 0 means no R8T, NO means R8T).
Based on this data, the MST2 initiates a status inquiry to the existing R8Ts.

This status inquiry is performed periodically, and any R
If there is an abnormality in the response of 8T, this is notified to CPU1.

In addition, once an abnormality in R8T is detected,
The status inquiry from MST2 to T is discontinued to save wasted time, and MST2 performs return detection using a longer cycle to detect return of abnormal R8T.

During this time, the CPUI uses the normal R8T to send and receive data.

The R8T that was once abnormal due to the recovery detection of MST2
When the recovery of R8T is detected, this is notified to the CPUI, and thereafter, the CPU 1 sends and receives data to and from this R8T as necessary.

By the way, in addition to inquiring about the status of R8T as described above, MST2 performs a self-return operation in which the transmission destination address is its own address, and tests its own transmitting/receiving circuit 6. In this case, as shown in Figure 3,
MST2 transmits the test signal to a modulation circuit 9 and a transmission driver 10.
A method of performing a test by once outputting the signal to the transmission line 3 through the receiver 11, the selector 12, and the demodulation circuit 13 and then returning it to the microprocessor 5;
There is a method of testing by switching the selector 12 and immediately returning the modulation signal from the modulation circuit 9 to the demodulation circuit 13. Therefore, using these two methods, it can be determined whether the transmission driver 10 and receiver 11 of the transmission/reception circuit 6 of the MST 2 are abnormal, or whether the modulation circuit 9 and demodulation circuit 13 are abnormal. Note that this result also applies to the failure and recovery of the transmission/reception circuit 6 of the MST itself.
will be notified.

According to this embodiment, the master station 2 automatically detects the return of an abnormal remote station and reports this to the CP.
Since the CPU 1 notifies U 1, the CPU 1 can quickly reuse the returned remote station. Further, since the master station 2 can perform a self-return test, even if an abnormality is initially detected in R8T, it is possible to distinguish whether the abnormality is in R8T or MST2 by this self-return test. Therefore, since it can be immediately determined which part is abnormal, troubleshooting can be carried out quickly and the operation rate of the equipment fh' can be improved.

〔Effect of the invention〕

As described above, according to the data transmission method of the present invention, the master station independently of the central control unit detects not only an abnormality in a remote station but also the recovery of an abnormal remote station, and notifies the central processing unit of the abnormality. By performing a self-return test to detect the status of the master station itself, a remote station that has returned to positive power can be used immediately (7J), and it is also possible to detect an abnormality in the remote station and troubleshoot the problem. This has the effect of quickly resolving the situation.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an example of conventional data transmission = i-following,
FIG. 2 is a block diagram showing a simple example of a data transmission device to which the data transmission method of the present invention is applied, and FIG. 3 is a block diagram showing a detailed example of the mass transmission/reception circuit shown in FIG. 2. , Figure 4 shows the R8TO given by the CPU to MST.
It is a data explanatory diagram showing a lecture. DESCRIPTION OF SYMBOLS 1...Central processing unit, 2...Master station, 3...Transmission line, 41-4n...Remote station 7, 6...Transmission/reception circuit, 9...Modulation circuit, IO
...Transmission driver, 11...Receiver, 12...
- Selector, 13... demodulation circuit. Agent Patent Attorney Rules Kensuke Chika (and 1 other person) Figure 1, Figure 41)]

Claims (1)

[Claims] In a data transmission device in which a plurality of remote stations are connected to a transmission path exiting from a master station connected to a central processing unit, when the master station receives data indicating the existence or nonexistence of a remote station from the central processing unit, the master station It inquires of all the existing remote stations about the status of the station at a predetermined cycle, and when it detects a remote station with an abnormality, it reports this to the central processing unit, and at the same time detects the late closing of the abnormal remote station at a cycle longer than the above-mentioned cycle. The device has a means to report this to the central processing unit, and a self-loopback test in which the modulation signal it periodically outputs is immediately returned to the demodulation circuit to adjust its own status and correct its own abnormality or after the abnormality. A data transmission method characterized by having a means of reporting to a central processing unit.