JPH059052U - Bus communication device - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the same address is set or the addresses are duplicated due to a failure of the address setting means, these situations can be recognized quickly. Therefore, a serious situation in which communication becomes impossible is avoided in advance. [Structure] Each communication station monitors the tokens that are transmitted on the bus and the token transmission means that determines the timing when the token is output to the bus again after the token is received. If you receive a token earlier than when you issue a token, and if you receive a token earlier than when you issue a token, abandon the token and notify that the address is duplicated. And a warning command output means for outputting the command.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bus-type communication device in which a plurality of communication stations are connected via a bus and communication rights are carried between these communication stations by carrying communication rights (this is called a token). More specifically, the present invention relates to a bus type communication device capable of detecting a case where an address is duplicated and set in each communication station connected to a bus.

[0002]

[Prior Art]

 The token-pass bus-type communication device does not require a special device for communication control in the communication loop, and is widely used in process control devices. In such a communication device, address information is used for the token circulation, but the same address is erroneously set in two or more communication stations among the communication stations connected on the bus, or a failure occurs. If the address overlaps due to reasons such as the above, the token cannot be circulated normally, resulting in a serious situation in which communication is not possible. In the case of duplicate address settings, it is possible to visually check the erroneous settings if they are set incorrectly.However, if the address setting circuit fails, It's not easy to discover.

In the conventional device, it is assumed that a normal address is set in each communication station connected to the bus, and a device that has a function of detecting an address duplication is provided. There wasn't.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of such a point, and enables a failure of an address setting circuit and an erroneous setting of an address to be quickly detected, and a serious situation of communication failure can be avoided in advance. An object is to provide a communication device.

[0005]

Means for Solving the Problems In the present invention to achieve such an object, a plurality of communication stations each having an address set are connected via a bus, and a token is used as the address information between the communication stations. In a bus-type communication device that carries out communication based on the above, token transmission means in which each communication station determines a different timing by changing the timing of receiving the token and then outputting the token to the bus again And a token monitoring means that monitors the token circulating on the bus and receives a token earlier than the timing of issuing the token, and a token monitoring means that monitors this token earlier than the timing of issuing the token. When it is received, it discards the token and outputs a command notifying that the address is duplicated. An alarm command output means is provided, a bus type communication device is characterized in that as each communication station outputs an alarm message when an address duplication receiving the alarm command.

[0006]

[Action]

 An address is set for each of the plurality of communication stations, and the communication station that obtains the next communication right is specified by the address information and the token is circulated. Here, if the addresses are duplicated, the communication right will be obtained at those communication stations, but the timing (time) from the reception of the token to the next transmission of the token will be different. Since they are different, at any communication station, the token monitoring means will detect that the token is received earlier than the timing at which it issues the token.

In this case, the alarm command output means in the communication station abandons its token and outputs a command notifying that the addresses are duplicated on the bus.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the present invention. In the figure, BS is a bus to which each communication station is connected. Here, only the configuration of one communication station connected to the bus is shown, but other communication stations have the same configuration. Reference numeral 1 is a communication interface with the bus BS, and 2 is an address setting means for setting an address for specifying this communication station, which is, for example, mechanically set or software set. Numeral 3 is a token receiving means for receiving a token circulating on the bus BS, and when the token comes around to the communication station of its own, the communication can be executed using the bus BS. Reference numeral 4 denotes a token transmitting means for transmitting the token on the bus Bs after the token receiving means 3 receives the token. The timing (time) until the token is output to the bus again after the token is received is indicated in each communication. It is configured so that it can be changed differently depending on the station.

Reference numeral 5 is a token monitoring means for monitoring the token on the bus BS and judging whether or not the token is received earlier than the timing at which the token is issued by itself. When it detects that a token is received early, it abandons the token to be output by itself and outputs a command on the bus for notifying that the address is duplicated. Alarm command output means, 7 is an alarm command output means. This is an alarm message output means for outputting an alarm message of address duplication when an alarm command sent from 6 or from another communication station via the bus BS is received. The man-machine interface function of each communication station is used as the alarm message output means.

The operation of the apparatus thus configured will be described below. FIG. 2 is a conceptual diagram for explaining the operation. Here, the communication stations ST1 to ST4 are connected to the bus BS, and each communication station has an address, “1” for the communication station ST1, “2” for the communication station ST2, and “2” for the communication station ST3. Is set to “3”, and “2” is erroneously set redundantly in the communication station ST4. Now, assume that the communication station ST1 (address 1) outputs a token for communication (designates address 2) and the communication station ST2 (address 2) receives it. In this case, the communication station ST4 (address 2) also receives the same token. After receiving the token, the communication stations ST2 and ST4 try to output the token to the communication station ST3 (address 3). In the present invention, in the two communication stations ST2 and ST4, it is determined that the token transmission means 4 does not output the token at the same timing. For example, the communication station ST2 sends the token on the bus BS earlier than ST4. Will be output to.

The token monitoring means 5 of the communication station ST4 detects this token output on the bus BS and recognizes that another communication station is outputting the token before it outputs the token. .. Receiving this judgment, the alarm command output means 6 abandons the token received by the communication station ST4 (abandons sending of the token by itself) and sends a command on the bus BS to notify that the addresses are duplicated. Output. Further, if the communication station ST4 is equipped with an alarm message output means 7 as a man-machine interface, an alarm of address duplication is output there. Further, even in another communication station that has received the command for notifying the address duplication via the bus BS, if the communication station is equipped with the alarm message output means 7 as the man-machine interface, the address duplication is detected there. Output an alarm. This allows each communication station to quickly know the state in which the addresses are duplicated.

In this description, the case where the communication station ST2 outputs the token before ST4 is taken as an example. However, when the communication station ST4 outputs the token at a timing earlier than ST2, the communication station ST2 side outputs the token. Will be abandoned and a command for notifying the same address duplication as described above will be sent to the bus BS.

[0013]

[Effect of the device]

 As described in detail above, according to the present invention, the same address can be set by allowing the timing of outputting the token to the bus to be arbitrarily changed in each communication station and different in each communication station. Even in the case where the addresses are duplicated due to the failure of the address setting means or the like, it is possible to quickly detect these situations and recognize them. Therefore, it is possible to avoid a serious situation where communication becomes impossible, and it is possible to provide a bus type communication device having high reliability and maintainability.

[Brief description of drawings]

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

FIG. 2 is a conceptual diagram for explaining an operation.

[Explanation of symbols]

 BS bus ST1 to ST4 communication station 1 communication interface 2 address setting means 3 token receiving means 4 token transmitting means 5 token monitoring means 6 alarm command output means 7 alarm message output means

Claims (1)

[Claims for utility model registration] [Claim 1] A plurality of communication stations each having an address set are connected via a bus, and a token is carried between these communication stations based on the address information for communication. In the bus type communication device that executes the above, the communication circuit circulates on the bus with the token transmission means in which the timing of receiving the token to the communication station and then outputting the token to the bus is made variable and the communication station determines different timing. Token monitoring means that monitors the token and receives the token earlier than the token issuing time, and if this token monitoring means receives the token earlier than the token issuing time, abandon the token And an alarm command output means for outputting a command notifying that the addresses are duplicated. Only, each communication station bus type communication device is characterized in that so as to output a when the address duplication alarm message received the alarm command.