JPH0511588U - Communication control device - Google Patents

Abstract

(57) [Summary] [Purpose] The entire network does not become incommunicable even if it joins the network or the address overlaps at two or more stations during normal operation. Allows communication to be maintained between other stations. [Configuration] Each station connected to the network
The transceiver 1 and the communication controller basic unit 2 that receives and sends data via the transceiver by receiving a token addressed to its own station, and monitors whether the frame sent by itself completes normally without collision. , A transmission monitoring unit 3 that outputs a transmission abnormality signal when an abnormality occurs
And a reception monitoring unit 4 that monitors whether another station is transmitting for a certain period of time during a joining operation to the network and outputs a reception abnormal signal when there is an abnormality, and is output from the transmission monitoring unit 3 and the reception monitoring unit 4. The occurrence of transmission and reception abnormal signals is counted, and the monitoring counter 5 that is reset in a normal state and the disappearance time of the carrier on the network are measured,
A carrier monitoring circuit 6 that outputs a joining signal when the loss time exceeds a predetermined time is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a communication control device in a communication system configured by connecting a plurality of stations to the same transmission line (network), and more specifically, to perform communication control by circulating a communication right (token or baton). The present invention relates to a communication control device in which measures are taken when the same address is set in the network.

[0002]

[Prior Art]

 In a token bus type communication system in which tokens are circulated for communication control, the destinations of transmitted / received data are distinguished by station addresses individually set in each station. Then, if the same address is duplicated and set in the network, there is a problem that normal token transmission becomes impossible and the entire network becomes incommunicable.

Here, the following example is an example in which two stations set to the same address become unable to communicate when trying to join the network ring. (1) A station that has already joined the token ring invites a new station with a diagnostic token. (2) Two stations respond at the same time. (3) The solicited station erroneously recognizes that the token was successfully delivered because the frame was transmitted on the line. (4) The token is lost due to misrecognition. (5) For example, a new token is generated by mastership control in which the station with the smallest station number generates a token. (6) Offer solicitation. (7) Return to (2) and repeat.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of such a problem, and when a plurality of stations connected on a token bus type network have duplicate station addresses, the entire network becomes incommunicable. Rather, it is an object of the present invention to provide a communication control device that improves reliability by excluding only stations with overlapping addresses from the network and allowing communication between other stations to continue.

[0005]

[Means for Solving the Problems]

 The present invention, which solves such problems, provides a communication system composed of a plurality of stations connected on a token bus type network, where each station is provided with a transceiver connected to the bus type network and its own station. The communication controller basic part that receives a token to receive and send data via the transceiver and whether the frame sent by itself via this transceiver completes normally without collision. A transmission monitoring unit that outputs an abnormal signal, a reception monitoring unit that monitors whether other stations are transmitting for a certain period of time during a network joining operation, and outputs a reception abnormal signal when there is an abnormality, the transmission monitoring unit and the reception unit The occurrence of abnormal transmission and reception signals output from the monitoring unit is counted and And a carrier monitoring circuit for measuring the loss time of the carrier on the network and outputting a join signal to the network when the loss time exceeds a predetermined time. The communication control device is characterized in that when the count value of the monitoring counter exceeds a predetermined value, it is determined that stations with the same address are duplicated on the network, and the station is abnormally displayed and stopped. .

[0006]

[Action]

 The monitoring counter counts the transmission abnormality detection signal and the reception abnormality signal output from the transmission monitoring unit and the reception monitoring unit after receiving the frame of invitation to subscribe to itself. Also, the carrier monitoring unit detects the disappearance of the token from the network that occurs when the same address is set on the network. When the token disappearance is detected, the join signal is turned on and the Start monitoring operation.

When the count value of the monitor counter exceeds a predetermined value, the communication controller basic unit determines that stations with the same address are duplicated on the network.

[0008]

【Example】

 An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the present invention. In this figure, the communication controller part of one station connected to the network is shown, but it is assumed that other communication stations have the same configuration. In the figure, LAN is a token bus type network, to which a plurality of stations are connected to form a communication system.

1 is a transceiver connected to a bus type network LAN, 2 is a token addressed to its own station (address assigned to its station), and transmits / receives data via the transceiver 1. This is the basic part of the communication controller and contains a microprocessor and other components. Reference numeral 3 is a transmission monitoring unit that monitors whether or not the frame transmitted by itself via the transceiver 1 completes normally without collision, and outputs a transmission abnormality signal when there is an abnormality. Reference numeral 4 denotes a reception monitoring unit that monitors whether another station is transmitting for a certain period of time during a joining operation to the network LAN, and outputs a reception abnormality signal when an abnormality occurs. Reference numeral 5 is a monitoring counter that counts the occurrence of abnormal transmission and reception signals output from the transmission monitoring unit 3 and the reception monitoring unit 4, and is configured to be reset under normal conditions. A carrier monitoring unit 6 measures the disappearance time of the carrier on the network LAN and outputs a join signal to the network LAN to the communication controller basic unit 2 when the disappearance time exceeds a predetermined time.

When the count value of the monitoring counter 5 exceeds a predetermined value, the communication controller basic unit 2 judges that there are two or more stations with the same address on the network LAN, and displays that station as an error. Then, it is stopped and excluded from the network LAN. Further, when the carrier monitoring unit 6 detects that the carrier disappearance time has exceeded a predetermined time, it is determined that the token has disappeared, and in response to this, it is configured to join the network LAN. is there.

The operation of the device configured as described above is performed when there are two stations with the same address when the station joins the network, and when there is a station with an overlapping address due to, for example, a failure during normal operation. The following is a description of cases where they occur.

(When Two Stations with the Same Address Exist when the Station Joins the Network) FIG. 2 shows the time when two stations with the same address respond at the same time when the station joins the network. It is a chart. At the timing shown in (a), when a solicitation to the user is made, that is, when a frame with an address is received from the network LAN side, the reception monitoring unit 4 starts reception monitoring as shown in (d) at this point. . Two stations corresponding to the specified address (one of which is a duplicate address station) simultaneously send a join response at the timings shown in (b) and (c) (reception monitoring is not possible while sending a join response). It is supposed to be). The transmission monitoring unit 3 starts transmission monitoring as shown in (f). At this time, however, it is also monitored that other stations (stations with duplicate addresses) have responded. ) Immediately output the transmission error detection signal as shown in (). The monitoring counter 5 counts up in response to the transmission abnormality detection signal.

Eventually, the two stations will be recruited again. If the station can join normally, the monitoring counter 5 is cleared, but if the two stations simultaneously respond to the joining, a transmission error detection signal is output and the monitoring counter 5 counts up again. . When such a state is repeated, the monitoring counter 5 eventually exceeds a certain value. The communication controller basic unit 2 receives a signal whose count value exceeds a certain value from the monitoring counter 5, determines that there is a station with the same address on the network LAN, and indicates that the station is abnormal. To stop responding to solicitations to join.

FIG. 3 is a time chart when a station joins a network and two stations having the same address respond to each other with a slight response time difference.

In this case, the join response of the duplicate station is delayed by t with respect to the join response of the station of another same address. Since the reception monitoring unit 4 detects that it is already receiving at another station, it outputs a reception abnormality signal as shown in (e). The monitoring counter 5 receives the reception detection signal and counts up. Then, in the same manner as described above, the monitoring counter 5 eventually exceeds a certain value, and the communication controller basic unit 2 receives a signal from the monitoring counter 5 that the count value exceeds the certain value. It is determined that there is a station with the same address in.

(Case where Stations with Duplicate Address Occur During Normal Operation) FIG. 4 is a time chart showing the operation in this case. When a normal token arrives at itself as shown in (a), a response is sent as shown in (b). The duplicated station also sends the response in the same way as shown in (c). As a result, multiple responses will be returned on the network, and the token cannot be delivered normally, and the token will disappear. When the token disappears, the frame cannot be transmitted from the network LAN. The carrier monitoring unit 6 monitors the carrier on the network LAN, and when the carrier is no longer detected and a certain time (a little longer than the time for which the token makes one round) has passed, the disappearance of the token is set to (d). It detects as shown and outputs a join signal.

Each station has a function of generating a token (mastership control function) in case the token is lost, and this station can be controlled by this mastership control among the stations that join the network. The winning station will generate a new token after the token disappears. The station that receives this signal performs the same monitoring operation as in the case shown in FIG. 2 since the joining signal is in the ON state.

In this embodiment, each monitoring unit and counter are shown as blocks separate from the communication controller basic unit, but each of these functions may be realized by a program of a microprocessor.

[0019]

[Effect of the device]

 As described in detail above, according to the present invention, in the case where a plurality of stations connected to the network join the network, or when two or more stations have overlapping addresses during normal operation. Even if it happens, by surely detecting such a situation and disconnecting it from the network, it is possible to maintain communication between other stations without causing the state where the entire network becomes incommunicable. . Therefore, it is possible to provide a highly reliable communication control device.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart in the case where two stations having the same address simultaneously respond to join when the station joins the network.

FIG. 3 is a time chart when two stations having the same address respond to each other with a slightly different response time when joining the network.

FIG. 4 is a time chart showing an operation in the case where a station having an overlapping address occurs during normal operation.

[Explanation of symbols]

 LAN Token bus type network 1 Transceiver 2 Communication controller basic part 3 Transmission monitoring part 4 Reception monitoring part 5 Monitoring counter 6 Carrier monitoring part

Claims (1)

Claims for utility model registration: 1. In a communication system comprising a plurality of stations connected on a token bus type network, each station has a transceiver connected to the bus type network, The communication controller basic part that receives a token addressed to the station and sends and receives data via the transceiver and the frame sent by itself via this transceiver is monitored to see if it completes normally without collision. A transmission monitoring unit that sometimes outputs a transmission abnormality signal, a reception monitoring unit that monitors whether another station is transmitting for a certain period of time during a network joining operation, and outputs a reception abnormality signal when there is an abnormality, and the transmission monitoring unit And count the occurrence of abnormal transmission and reception signals output from the reception monitoring unit, The communication controller basic unit is provided with a monitoring counter that is constantly reset, and a carrier monitoring circuit that measures the loss time of carriers on the network and outputs a join signal to the network when the loss time exceeds a predetermined time. Is a communication control device, wherein when the count value of the monitoring counter exceeds a predetermined value, it is determined that stations with the same address are duplicated on the network, and the station is abnormally displayed and stopped.