JPH10150454A - Control meter communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and speedily set the parameter of a slave station by simultaneously receiving communication commands from a master station in the slave station of a specified station number and preventing a response from being returned to the master station. SOLUTION: The same parameters are set for the groups of the slave stations A, B and D and the respective groups of the slave stations C and E. The station numbers 91 are set in the slave stations of the groups A, B and D and station numbers 90 for the slave stations of the groups C and E. When commands are transmitted from the master station 10 to the control meters of the slave stations A, B and D, the slave stations A, B and D execute reception processings, and recognize that they are respectively at broadcasting modes. Then, a transmission processing is executed and the slave stations A, B and D are at the broadcasting modes. Thus, the response is not returned to the master station and the transmission processing is terminated. Thus, the responses of the slave stations A, B and D do not collide and the abnormality of a communication operation does not occur. The slave stations C and E execute the similar processings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication system for a controller used for general instrumentation control, and more particularly to communication between a plurality of controllers and a personal computer (hereinafter referred to as a personal computer).

[0002]

2. Description of the Related Art Conventionally, controllers used for general instrumentation control, for example, flow rate control and cascade control, reactor cascade control, backup control, universal two-input selection control, and temperature / humidity control are well known. .

[0003] Some of such controllers are provided with a communication interface so as to be able to communicate with various devices. For example, there is one in which a plurality of controllers of this type are used as slave stations, a personal computer is connected as a master station, and a data link for reading and writing registers of the controllers by communication is constructed.

In such a case, as shown in FIG. 5, a master station 10 and slave stations 20 (A, B, C, D, and E are collectively referred to as 20) are physically connected to each other via a communication line 30. The station numbers (STn) of the slave stations (A to E)
01), 02, 03, 0 respectively so that o) does not overlap
As 4,05, PC link communication is performed one by one,
It is configured to set parameters.

In such a configuration, for example, when the parameters of the controllers of the slave stations A, C, and E are set to the same value, a command for A is transmitted from the master station 10 and the response is received. , C, and E are communicated in a similar procedure.

The format of the personal computer link communication command is as shown in FIG. 6, and STX is a control code indicating the beginning of a command character string, a CPU
The number is, for example, 01. The response waiting time is ignored here. The command specifies a command from the master station, and the data corresponding to the command specifies a device name, the number of data points, parameters, and the like according to the command.

[0007] The checksum is a checksum from the next character of STX to the position before the checksum, and ETX is a control code indicating the end of the command character string.
CR is a control code indicating the end of the command.

[0008]

In the above system, communication is not possible unless the station numbers of the slave stations are independent of each other. Therefore, the transmission command from the master station can be issued to only one slave station at a time.

Therefore, a plurality of controllers, for example, A,
Even if it is desired to set the slave station groups C and E and the slave station groups B and D to the same setting for each group, it is necessary to separately communicate with the controllers A to E one by one.

In the conventional configuration, if the same station number is set to a plurality of slave stations in order to simultaneously communicate with a plurality of slave stations with one command, the slave station receiving the command returns a response to the master station. In order to do so, there has been a problem that a plurality of slave stations simultaneously perform transmission processing to the master station, and normal communication cannot be performed.

[0011] As a concept of personal computer link communication, a method of always returning a response when a command is received has been a conventional idea, and a system such as a broadcast mode has not been adopted in this type of system.

In view of the above, an object of the present invention is to
Controller communication that allows the slave stations to receive simultaneously in pair-to-n communication, and that these simultaneously received slave stations do not return a response to the master station, thereby enabling easy and quick setting of slave station parameters. It is to provide a system.

[0013]

According to the present invention, there is provided a controller communication system in which a plurality of controllers are connected as slave stations to one master station. The slave station having the station number of (1) can simultaneously receive a communication command from the master station and does not return a response to the master station.

[0014]

The slave station performs the internal processing in response to the command from the master station, but does not return a response to the master station in the subsequent transmission processing if the set station number is a specific station number. If it is not a specific station number, a response is returned to the master station.

Therefore, when the same specific station number is set in a plurality of slave stations, parameters can be set for the plurality of slave stations quickly and easily.
In addition, since the return of the response from the slave station to the master station is omitted, the collision of the response does not occur, and the normal communication is guaranteed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. Now, as shown in FIG. 1, it is assumed that the same parameter is set for each of the groups of the slave stations A, B, D and the groups of the slave stations C, E, and the groups A, B, D
Station number 91 to the slave stations of
A station number 90 is set for each slave station of E.

FIG. 2 shows an example of assigning station numbers.
Station numbers 01 to 89 are set as real addresses for performing ordinary personal computer link communication, and station numbers 90 to 9 are used.
9 is a virtual address for performing broadcast mode communication. Note that the station number of the slave station is the master station 10
Can be set by a PC link communication command.

In such a state, a command is transmitted from the master station 10 to the slave stations of each station number.
The reception process in the slave station will be described next with reference to the flow in FIG. (1) The station number in the command (see FIG. 6) is 9
If it is 0 or more, the broadcast mode flag is set to 1, and if it is less than 90, the broadcast mode flag is set to 0. (2) Next, the content of the received command is checked, and a predetermined process is performed. (3) Create a response.

Thereafter, the slave station performs transmission processing as shown in the flow chart of FIG. That is, if the broadcast mode flag is 1, the process ends as it is, and if it is 0, the previously created response is transmitted and the process ends.

For example, when a command is transmitted from the master station 10 to the controllers of the slave stations A, B, and D, A, B, and D perform the above-described reception processing and recognize that each is in the broadcast mode. .

Next, transmission processing is performed, and since A, B, and D are in the broadcast mode, the transmission processing ends without returning a response to the master station. Therefore, the responses of the slave stations A, B, and D do not collide,
No abnormality occurs in the communication operation. Note that slave stations C and E
, The same operation as described above is performed.

The foregoing description of the present invention has been presented by way of illustration and example only of a particular preferred embodiment. Accordingly, the present invention has many modifications, without departing from its essence,
Clearly, variations can be made.

[0023]

As described above, according to the present invention, the following effects can be obtained. In the broadcast mode, communication with controllers having the same station number can be performed in a one-to-n connection relationship, and parameters for a plurality of controllers can be set quickly and easily. However, since the slave station in the broadcast mode does not send a response to the master station, no error is returned even if there are errors in commands and parameters. Therefore, sufficient care must be taken at the time of setting.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a controller communication system according to the present invention.

FIG. 2 is a diagram showing an example of station number assignment.

FIG. 3 is a reception processing flowchart.

FIG. 4 is a flowchart of a transmission process.

FIG. 5 is a diagram showing an example of station number setting in a conventional controller communication system.

FIG. 6 is a diagram showing a format of a personal computer link communication command.

[Explanation of symbols]

 10 master station 20, A, B, C, D, E slave station

Claims (3)

[Claims] A controller communication system in which a plurality of controllers are connected to one master station as slave stations, wherein a slave station having a specific station number can simultaneously receive communication commands from the master station. And a controller communication system configured not to return a response to the master station. 2. The slave station has a function of judging a station number specified by communication from the master station and, if the station number is a broadcast mode station number, terminating a subsequent transmission process without returning a response. The controller communication system according to claim 1, wherein 3. The controller communication system according to claim 1, wherein the same broadcast mode station number can be set to a plurality of slave stations.