JPH0294848A - Communication method for programmable controller network - Google Patents

Abstract

PURPOSE:To improve communication efficiency in a programmable controller(PC) network by sending a command in the broadcast system when the same command is sent to all other PCs from a predetermined PC. CONSTITUTION:A PC 1 generates an exclusive command in a PC network to be sent to all slave PCs and awaits the circulation of a token and sends the generated command to all slave PCs2, 3...n-1, n by the broadcast transmission when the token is preserved. In the case of receiving the command, the slave PCs2, 3...n-1, n generate a response respectively and await the circulation of the token. When the PC2 preserves the token, the PC2 returns the generated response to the PC1. Thus, even if number of the PCs is increased, since the transmission of the command from the master PC is finished in one token preservation time, the efficiency of the communication processing is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to each programmable controller (hereinafter referred to as
The present invention relates to a communication method for a PC network in which each of the PCs in a PC network in which a plurality of PCs are connected to each other with a PC (hereinafter referred to as a PC) as a node communicates with each other using a token passing method.

[Conventional technology] The token passing method is a method of passing control packets called tokens around a system network.
This is a communication method in which the node (communication device) receives the request and obtains the right to transmit.

Conventionally, when communicating between PCs using the token passing method in a PC network, the communication procedure consists of a master (temporary mask) PC that is arbitrarily determined as necessary, and a party to which the mask PC sends commands. It was a system in which communication was carried out on a one-to-one basis with the slave PC. That is, the mask PC creates a command to be sent to the slave PC, and sends the command to the slave PC when it holds the token. On the other hand, when the slave PC receives the command, it creates a response and sends the response back to the mask PC when it has the token.

FIG. 2 is a diagram showing an example of a command/response sequence between PCs in a PC network to which this type of conventional communication method is applied.

In this example, the system network consists of n laptops.
1, 2, -, n-1, n, and a transmission medium (link) that connects these nodes.

The vertical axis in FIG. 2 is the time axis. The token is PCI, P
C2,=,PCn-1,PCn,Pct.

It visits PC2, . . . in this order.

Here, the mask PC is determined depending on the need at that time. Now, when Pct is defined as a mask PC and the commands sent from Pct to each slave PC 2, 3--n are the same, the command-response sequence will be as follows.

First, the PCI creates a command and waits for a token to circulate. When PCI holds the token, PC2,
A command is sent to PC3... until the token holding time ends. In the example of FIG. 2, the token holding time ends after the command is sent to the PC3. on the other hand,
When PC2 and PC3 receive the command, they each create a response in response to the command and wait for the token to circulate. When PC2 receives the token, it returns a response to Pct, and Pct processes the response. Next, when the token is passed to PC3, PC3
Pct sends a response back to PC3, and Pct processes the response received from PC3. The token is also PC4゜...
・Although the tokens are sequentially delivered to PCn, since commands are not sent from PCl to these PCs, no response is sent back to PCl during each token holding time.

In this way, when the token circulates once and is handed over to Pct again, PCl sends a command to PC4 and PC5. In the example in Figure 2, Pct sends a command to two slave PCs during one token holding time. and n is an odd number. )
, PC2, and PC3 are executed (not shown). Even at this time, the token is PC2
, PC3, PC6゜..., it goes around to PCn,
No response is returned from these slave PCs.

By repeating this sequence, the tokens are (n −3
) After going around 72 times and passing it to Pct again, Pct
sends a command to PCn-1 and PCn, the same processing as described above is performed, and response processing from all slave PCs is completed.

[Problems to be Solved by the Invention] In the conventional PC network communication method described above, when sending the same command to all slave PCs, the number of mask PCs that create the command is equal to the number of partner PCs that exist in the PC network. command must be sent. As a result, if the number of PCs is large and commands cannot be sent to all slave PCs in one token holding time, the token needs to circulate several times to complete the command-response sequence. This has the disadvantage of reducing the efficiency of communication processing.

[Means for Solving the Problems] A communication method for a PC network according to the present invention is such that each PC in a PC network formed by connecting a plurality of PCs communicates with each other using a token passing method, with each PC serving as a node. In the PC network communication method that performs , sends a response back to the mask PC.

[Operation] When sending the same command to all slave PCs, the mask PC creates a command exclusively for the PC network,
When you have a Togokun, that command is sent to all slave PCs.
broadcast transmission (-broadcasting, i.e., a communication method in which the recipients of the information being sent are not specified, and all recipients who need and have the right to receive the information receive the information) do. When the slave PC receives the command, it creates a response and sends the response back to the mask PC when each slave PC has 1.-kun.

Therefore, even if the number of PCs increases, the transmission of commands from the mask PC can be completed within one token holding time, so the command-response sequence is completed when the token circulates once, improving the efficiency of communication processing. can be increased.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of a command/response sequence between internal ports in a PC network using the communication method of the present invention.

In this embodiment as well, the PC network consists of n PCIs, 2. ...consists of +, n, P
This is a case where Cl is determined as the mask PC. Further, the token circulates in the order of Pct, PC2, -PCnl, and PCn.

Pct creates a command exclusively for the PC network to send to all slave PCs, waits for the token to come around, and when it has the token, broadcasts the created command to all slave PCs 2, 3, -,
Send to n-1, n. Each slave PC2, 3,..., n-
When 1 and n receive the command, they each create a response and wait for the token to come around. When PC2 possesses the token, it returns the created response to PC1. When PCl receives the response, it processes the response. The same applies to PC3 to PCn.

[Effects of the Invention] As explained above, the present invention uses broadcasting when sending and receiving the same command from a specified PC to all other PCs when transmitting and receiving data between PCs in a PC network using the token passing method. By transmitting in this manner, commands can be sent to each PC in one token holding time, and as a result, the efficiency of communication within the PC network can be improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of a command/response sequence between PCs in a PC network using the communication method of the present invention, and Figure 2 is a diagram showing an example of a command/response sequence between PCs in a PC network using the conventional token passing method. FIG. 3 is a diagram showing an example of a response sequence. Co., Ltd.

Claims (1)

[Scope of Claims] A communication method for a programmable controller network, in which each of the programmable controllers in the programmable controller network is formed by connecting a plurality of programmable controllers, each of which is a node, and the programmable controllers communicate with each other using a token passing method. , A master programmable controller arbitrarily determined as necessary transmits a command in a broadcast manner when it holds a token, and each slave programmable controller, when it holds a token, sends a command to the master programmable controller. A communication method for a programmable controller network, characterized in that a response is sent back.