JPH0445869B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a data transmission load control system based on a bus configuration, and in particular, to a method for disconnecting an abnormal bus by bus diagnosis suitable for use in a distributed control system, etc. The present invention relates to a load control system based on the method.

[Prior Art] FIG. 4 is a block diagram showing a load control system based on the conventional abnormal bus disconnection method disclosed in, for example, Japanese Patent Laid-Open No. 61-22494. In the figure, 1 is a sub-bus (transmission bus), 7 is a plurality of transmission devices connected to the sub-bus 1, and this transmission device 7 has a sub-bus monitoring control circuit 16 and a switch circuit 22.

The sub-bus monitoring control circuit 16 includes a transmitting circuit 17,
It is composed of a receiving circuit 18, a transmission control circuit 19, a central processing unit (hereinafter abbreviated as CPU) 20, and a watchdog timer 21, and the input side of the watchdog timer 21 that detects timeout is connected to the CPU 20. . A switch circuit 22 that connects and disconnects the sub-bus supervisory control circuit 6 from the sub-bus 1 is comprised of a relay contact 23 and a relay coil 24.

Next, the operation will be explained. Transmission control circuit 19
converts the output of the CPU 20 into a transmission format determined by the sub-bus 1 and sends it to the transmitting circuit 17, and also restores and error-controls the data received from the receiving circuit 18, and transfers the data to the CPU 20.

While data transmission is being performed, a normal transmission signal is periodically output from the CPU 20 to the watchdog timer 21, and the watchdog timer 21 is reset to its initial state. At this time, the abnormality detection level is set in the watchdog timer 21,
This abnormality detection level is not reached because it is reset periodically.

Therefore, the output of the watchdog timer 21 is
The relay coil 24 is energized, and the relay contacts 23 are always closed.

However, for example, if a failure occurs in any of (a) the other transmission device 7, (b) the sub-bus 1, (c) the transmission circuit 17, the reception circuit 18, or (d) the transmission control circuit 19, data transmission may be interrupted. do.

When data transmission is interrupted, a transmission normal signal is not output from the CPU 20 to the watchdog timer 21. If the watchdog timer 21 does not receive a transmission normal signal for a certain period of time, it reaches the abnormality detection level and outputs no longer, the relay coil 24 is de-energized, the relay contact 23 is opened, and the sub-bus monitoring control circuit 16 is disconnected from the sub-bus 1. Separation [Problems to be Solved by the Invention] Since the conventional load control system is configured as described above, it is necessary for each transmission device to have an individual sub-bus monitoring control circuit and a switch circuit. For this reason, there have been problems such as difficulty in configuring a load control system with a hierarchical structure using a plurality of sub-buses.

This invention was made to solve the above-mentioned problems, and it eliminates the need for a sub-bus supervisory control circuit and a switch circuit in the transmission device itself, and creates a hierarchical structure using multiple sub-buses. The purpose is to make it easy to obtain a load control system with the following functions.

[Means for Solving the Problems] A load control system according to the present invention includes a main bus supervisory control circuit that connects a plurality of sub-buses in parallel to a main bus and monitors the main bus, and a main bus supervisory control circuit that monitors the main bus. A main bus monitoring device having a switch circuit that connects or disconnects the sub bus from the main bus based on an output is connected to the main bus.

[Function] The main bus monitoring device according to the present invention monitors the main bus with the main bus monitoring control circuit, and when an abnormality is detected, the sub-bus with the abnormality is separated from the system using the switch circuit, thereby connecting to the sub-bus. It is no longer necessary to provide a sub-bus monitoring and control circuit in the transmission equipment itself.
The configuration is simplified, and it becomes easy to configure a hierarchically structured load control system using a plurality of sub-buses.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, in which the same parts as in FIG. The monitoring device 3 has a main bus monitoring and control circuit 6 and a switch circuit 8 that connects and disconnects the sub-bus 1 from the main bus 2 based on the output of the main bus monitoring and control circuit, and both circuits 6 and 8 are connected to a control line. It is connected by 11.

The main bus monitoring control circuit 6 is the transmitting circuit 12
It consists of a receiving circuit 13, a transmission control circuit 14, and a central processing unit (hereinafter abbreviated as CPU) 15.
Further, the switch circuit 8 includes a relay contact 4 and a relay coil 5.

Each of the above-mentioned sub-buses 1 constitutes each subsystem such as security, equipment control, and video equipment control. Furthermore, the control signal transmission methods of these subsystems have the same protocols and electrical conditions.

Next, the operation will be explained. When data transmission is normally performed on all the sub-buses 1 connected to the main bus 2, the main bus supervisory control circuit 6, which monitors the state of the main bus 2, transmits data via the control line 11. The relay coil 5 is excited and its relay contact 4 is always closed. Therefore, the transmission device 7 connected to each sub-bus 1
communication is possible via the main bus 2, and the transmission device 7 operates in conjunction, resulting in a more convenient system.

Here, if an abnormality occurs in the transmission device 7 connected to the sub-bus 1 or in the sub-bus 1 itself, the main bus monitoring control circuit 6
Abnormalities on the main bus 2 are detected from signals other than the predetermined protocol input to the CPU 15 through the main bus 2.

When an abnormality is detected in the main bus 2, the sub-bus 1 in which the abnormality has occurred is detected according to the flow shown in FIG. The main bus supervisory control circuit 6 operates the transmission control circuit 14 based on the output of the CPU 15, sequentially de-energizes the relay coil 5 and sequentially opens the relay contacts 4, and each time the relay contact 4 is opened, the main bus 2
monitor. If an abnormality is detected on the main bus 2 again, the relay coil 5 is energized and the relay contact 4 is closed. If no abnormality is detected on the main bus 2 again, the relay coil 5 is kept de-energized, the relay contact 4 is opened, and the CPU 15 detects that an abnormality has occurred on the sub-bus 1.
The abnormal sub-bus 1 is detected by outputting from the CPU 15 and notifying the transmission device 7 on the sub-bus 1 connected to the main bus 2 by the transmitting circuit 12, or by notifying the main bus monitoring device 3 by the output of the CPU 15 ( Steps 3-1 to 3-7).

If the main bus 2 or sub-buses 1 at two or more locations
If an abnormal bus cannot be detected using the control flow described above, such as when there is an abnormality in the Then, the sub bus 1 is separated from the main bus 2, and the signal is passed through the receiving circuit 13 of the main bus monitoring control circuit 6.
The CPU 15 detects an abnormality in the main bus 2 (steps 3-8 and 3-9). If an abnormality is detected, all subsystems are kept open, and the output of the CPU 15 notifies the main bus monitoring device 3 that there is an abnormality in the main bus 2 (step 3).
-7). If no abnormality is detected, the relay coils 5 are sequentially excited by the output of the CPU 15, all open relay contacts 4 are sequentially closed, and the sub-bus 1 is sequentially connected to the main bus 2. The main bus 2 is monitored every time the sub bus 1 is newly connected (steps 3-10 to 3-13). If no abnormality is detected on the main bus 2, the sub bus 1 is left connected. If an abnormality is detected, the relay contact 4 is opened again, the sub-bus 1 where the abnormality has occurred is disconnected, the CPU 15 outputs that an abnormality has occurred on the sub-bus 1, and the transmission circuit 12 connects it to the main bus 2. The bus in which the abnormality has occurred is detected by notifying the transmission device 7 on the sub-bus 1 that is abnormal, or by notifying the main bus monitoring device 3 by the output of the CPU 15 (step 3-14,
3-15). It is even more effective if the transmission device 7 or main bus monitoring device 3 that receives this notification displays this result.

In addition, even if data transmission is performed normally, the main bus control circuit 6 may cause some sub-buses to
By separating the two main bus systems, it is possible to configure a subsystem that can operate separately from the main bus 2 system.

FIG. 3 is a block diagram showing another example of the switch circuit 8 applied to the present invention. By adding a power supply 9 and a manual switch 10 as manual opening/closing means, the sub-bus 1 which has been disconnected due to a failure etc. , it can be easily reconnected to or separated from the main bus 2 by manual operation.

[Effects of the Invention] As described above, according to the present invention, a plurality of sub-buses are connected in parallel to a main bus, and a main bus supervisory control circuit that monitors the main bus, and a main bus supervisory control circuit that monitors the main bus, and a Since a main bus monitoring device having a switch circuit for connecting and disconnecting the sub-bus from the main bus is connected to the main bus, it is necessary to provide a sub-bus monitoring control circuit, etc. to the transmission device itself connected to the sub-bus. This has the advantage that the configuration is simplified, and a hierarchically structured load control system can be easily obtained using a plurality of sub-buses.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a load control system according to an embodiment of the present invention, Fig. 2 is a flowchart explaining the operation of Fig. 1, and Fig. 3 shows another example of a switch circuit applied to the present invention. FIG. 4 is a block diagram showing a conventional load control system. In the figure, 1 is the sub bus, 2 is the main bus,
3 is a main bus monitoring device, 4 is a relay contact, 5 is a relay coil, 6 is a main bus monitoring control circuit, 7
is a transmission device, 8 is a switch circuit, 9 is a power supply, 10
is a manual switch. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A sub-bus in which a plurality of transmission devices are connected in parallel, a main bus in which a plurality of the sub-buses are connected in parallel, and a main bus monitoring device that monitors the main bus; The monitoring device includes a switch circuit for connecting and disconnecting the sub-bus from the main bus, and monitors the state of the main bus, and if an abnormality is detected, opens the switch circuit to disconnect the sub-bus in which the abnormality has occurred from the main bus. A load control system characterized by comprising a main bus monitoring control circuit that separates the main bus. 2. The main bus monitoring device has means for sequentially connecting and disconnecting a plurality of sub-buses to the main bus using a switch circuit, and monitors the main bus each time each of the sub-buses is connected and disconnected, and identifies a sub-bus in which an abnormality has occurred. 2. The load control system according to claim 1, wherein the load control system detects and releases only the sub-bus. 3. The load control system according to claim 1 or 2, wherein the switch circuit has a manual opening means.