JPH0583020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reset control method for a local area network system that resets a specified station and a failed station.

A local area network system is constructed in which terminal devices are distributed over relatively short distances, for example, within several hundred meters, and are interconnected by transmission paths. In such a system, it is necessary to perform a reset and restart when a failure such as a program runaway occurs, and it is desired to be able to easily and economically control the reset.

[Conventional technology]

FIG. 4 is a block diagram of a conventional local area network system, in which 41 is a transceiver, 42 is a terminal device, 43-1 to 43-n are stations, 44 is a transmission path, 45 is a driver, and 46 is a Receiver, 47 is processor CPU, 48 is bus, 4
9 is a read-only memory that stores programs, etc.
ROM, 50 is random access memory RAM,
51 is a terminal interface part IF, 52 is a bucket assembly/disassembly adapter, 53 is a carrier detection circuit,
54 is a reset line, and R is a terminal resistance of the transmission line.

Each station 43-1 to 43-n is connected to a transmission line 44 via a transceiver 41.
, a driver 45 for sending data to the transmission line 44, a receiver 46 for receiving data on the transmission line 44, and a processor 47 for controlling each part.
bus 48, memories 49, 50, end interface section 51, bucket assembly/disassembly adapter 52
A packet assembly/disassembly adapter 52 and a processor 47 determine whether or not the message is addressed to the own station, and the message addressed to the own station is sent to the terminal via the terminal interface unit 51. The message from the terminal device 42 is transferred to the terminal device 42, the destination of the other station is added, and when the carrier detection circuit 53 detects that the transmission path 44 is empty,
Packets assembled by the packet assembly/disassembly adapter 52 are sent from the driver 45 to the transmission line 44.

In addition, when it is detected that the transmission path 44 is empty and multiple stations start transmission at the same time, a collision due to simultaneous transmission is detected, transmission is stopped, and retransmission is started after a predetermined time.For example, the CSMA/CD method. is also known.

Furthermore, the transceiver 41 and the terminal device 42 may enter a program runaway state due to external noise, power supply voltage fluctuations, and the like. In such a case, it is necessary to reset and restart from the initial state. For this purpose, a method is known in which, for example, software processing such as a watchdog timer is used to detect program runaway and reset the program. However, this method is not perfect, so a method that resets using hardware is better. For example, there are known systems that provide a power-on reset function that resets when the power is turned on, and systems that provide a reset switch.

However, it is necessary to perform a reset operation at the location where the terminal devices 42 are arranged, and since each terminal device 42 is distributed, the reset operation is not easy, and it is difficult to reset multiple terminal devices 42 at the same time. It becomes difficult. Therefore, as shown in the figure, a system is adopted in which a reset line 54 is provided to enable the reset operation from one location. for example,
By inputting a reset from the terminal device 42 of the station 43-1, it becomes possible to reset the other stations 43-2 to 43-n connected to the reset line 54 at the same time.

This reset line 54 is provided separately from the transmission line 44 exclusively for reset, and can reset all stations, but it is impossible to reset only a designated station. In addition, the induced noise may propagate to each station and cause malfunctions.

Therefore, a specific station among the plurality of stations 43-1 to 43-n is designated as a master station, and the other stations are designated as slave stations, and a break time is assigned to the slave stations, and a break signal of the break time corresponding to the slave stations is transmitted. A method for resetting a specified slave station by sending
This is shown in Publication No. 85644.

[Problem to be solved by the invention]

In the conventional example shown in FIG. 4 described above, it is necessary to install a dedicated reset line 54, and there is a drawback that noise propagates to each station, causing malfunction, and the break signal described above is not transmitted. This method has the disadvantage that it is not possible to reset a station in which a failure occurs in which the break signal cannot be determined.

An object of the present invention is to enable a master station to issue a reset command to a designated station or a failed slave station.

[Means to solve the problem]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention,
11 is a transceiver, 12 is a terminal device, 13-1
43-n is a station, 14 is a transmission line, 15 is a reset rejection control circuit, 16 is a reset pulse detection circuit,
17 is a processor CPU, 18 is a bus, 19 is a read-on memory ROM, 20 is a random access memory RAM, 21 is a terminal interface IF, 2
2 is a packet assembly/disassembly adapter, 23 is a carrier detection circuit, 24 is a reset pulse sending circuit, 2
5 and 27 are drivers, 26 is a receiver, and R is a terminal resistance of the transmission line.

When communicating between the terminal devices 12 via the transmission path 14, as in the conventional example, when the carrier detection circuit 23 of the transceiver 11 does not detect a carrier, the transmission path 14 is empty, so the packet assembly/disassembly adapter 22 The packets assembled by the above and with a destination added thereto are sent to the transmission line 14 via the driver 25. The transceiver 11 of another station that receives this packet uses the packet assembly/disassembly adapter 22 and the processor 17 to determine whether or not it is addressed to its own station, takes in the packet addressed to its own station, and transmits it to the terminal device 12 via the terminal interface section 21. Transfer via.

The reset pulse sending circuit 24 sends out a reset pulse of a predetermined length that is set to be distinguishable from data, and is activated after the reset message is sent. This reset pulse sending circuit 24 only needs to be provided in the transceiver 11 of the master station, but it can be provided in the transceiver 11 of each station 13-1 to 13-n so that the master station can be set arbitrarily. You can also do it.

Further, the reset pulse detection circuit 16 detects the reset pulse sent from the master station and outputs the reset pulse to the terminal device 12.
and the processor 17, and if a prohibition signal is applied from the reset rejection control circuit 15, the reset pulse detection function is stopped, so even if a reset pulse is sent from the master station, No reset operation will be performed.

This reset rejection control circuit 15 does not apply a prohibition signal to the reset pulse detection circuit 16 when it determines that its own station has been designated by a reset message. A station that has lost its password will not be able to refuse a reset. In other words, the faulty station will be reset by the reset pulse even if it is not specified by the master station.

The functions of the reset rejection control circuit 15 and the reset pulse detection circuit 16 described above can also be realized by the processing functions of the processor 17.

FIG. 3 is an explanatory diagram of the operation of the embodiment of the present invention,
Station 13-1 is the master station, and other stations 13-2 to 13-
The case is shown in which the slave station 13-n is specified and reset with n as the slave station, and a failure has occurred in the slave station 13-i. When a command to reset n is input, in the transceiver 11, the processor 17 and the packet assembly/disassembly adapter 22 create a reset message specifying the slave station 13-n as the destination by the slave station number, etc., and the driver 25 transmission line 14 via
Send to.

Each slave station 13-2 to 13-n applies this reset message to the packet assembly/disassembly adapter 22 via the transceiver 26, analyzes the message by the processor 17, and determines whether the message is addressed to the local station or not. Since the reset message is not addressed to the non-designated slave station 13-2, the reset rejection control circuit 15 controls the reset rejection. That is, a prohibition signal is applied to the reset pulse detection circuit 16 to stop the reset pulse detection operation.

Furthermore, since the failed slave station 13-i cannot analyze the reset message, the reset rejection control circuit 15 does not operate regardless of whether or not the own station is designated. Further, in the designated slave station 13-n, the reset rejection control circuit 15 does not operate because the reset message is analyzed as being addressed to the own station.

The master station 13-1 activates the reset pulse sending circuit 24 after a certain period of time after sending the reset message, and sends a reset pulse to the transmission line 14 via the driver 27.

Each slave station 13-2 to 13-n applies this reset pulse to the reset pulse detection circuit 16 via the carrier detection circuit 23, and when it detects the reset pulse, applies a reset signal to the terminal device 12 and processor 17. The reset pulse detection circuit 16 to which the prohibition signal is applied from the reset rejection control circuit 15 does not detect a reset pulse. Therefore, although the non-designated child station 13-2 is not reset, the failed child station 13-i and the designated child station 13-n are reset and can restart.

Therefore, the designated child station 13-n and the faulty child station 13
-i can be reset. Mata child station 13
When resetting all of -2 to 13-n, it is sufficient to send a reset pulse after sending a reset message using a broadcast destination. Furthermore, since the reset rejection control circuit 15 does not operate in the sequence of sending out a reset pulse without sending out a reset telegram, all slave stations 13-2 to 13-n can be reset at the same time.

〔Effect of the invention〕

As explained above, the present invention is applicable to a plurality of stations 3 in a local area network system.
- Set any station among 1 to 3-n as a master station, and after transmitting a reset message specifying any slave station or all slave stations from this master station, transmit a reset pulse,
If the slave station is not specified by the reset message, the reset rejection control unit 5 rejects the reset by the reset pulse, and other slave stations are reset by the reset pulse, so there is no need to install a dedicated reset line. There is an advantage that any slave station can be reset using hardware, and a slave station in which a failure has occurred can also be reset.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the invention, FIG. 3 is a diagram explaining the operation of the embodiment of the invention, and FIG. 4 is a conventional block diagram. 1 is a transceiver, 2 is a terminal device, 3-1 to 3
-n is the station, 4 is the transmission path, 5 is the reset rejection control section, 6 is the reset pulse detection section, and 7 is the processor.
CPU, 11 is a transceiver, 12 is a terminal device,
13-1 to 13-n are stations, 14 is a transmission line, 15 is a reset rejection control circuit, 16 is a reset pulse detection circuit, 17 is a processor CPU, 18 is a bus,
19 is a read-only memory ROM, 20 is a random access memory RAM, 21 is a terminal interface section IF, 22 is a packet assembly/disassembly circuit, 23
2 is a carrier detection circuit, and 24 is a reset pulse sending circuit.

Claims (1)

[Claims] 1. A local area network system in which a plurality of stations 3-1 to 3-n each having a transceiver 1 and a terminal device 2 are connected to a transmission line 4 via the transceiver 1. In the transceiver 1, a reset refusal control section 5 is provided.
and a reset pulse detection section 6, a specific station among the plurality of stations 3-1 to 3-n is designated as a master station, the others are designated as slave stations, and a reset is performed by specifying any slave station from the master station. After transmitting a reset message for performing the reset, a reset pulse is transmitted, and the slave station receives and analyzes the reset message with the transceiver 1, and detects the reset pulse with the reset pulse detector 6,
Only in the slave station that has determined that its own station is not designated by the reset message, the reset rejection control unit 5 rejects the reset, and other slave stations perform the reset upon detection of the reset pulse. A reset control method for a local area network system characterized by the following.