JPH11296211A - Input/output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for sharing a distributed I/O device connected through a communication line by plural distributed controllers. SOLUTION: In plural I/O devices connected to plural programmable controllers(PCs) through a network, each I/O device 11 is provided with 1st link buffers 31 to 33, and each of plural PCs 1 to 4 is provided with 2nd link buffers 41 to 43 corresponding to each I/O device 11 and a means for transmitting output data in each period, so that one I/O device 11 can be accessed from plural PCs on the network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an input / output device connected to a programmable controller (PLC).

[0002]

2. Description of the Related Art FIG. 5 shows a conventional input / output device. In the figure, 51 is a PLC master station, and 52 and 53 are P
LC and 61 are input / output devices (slave stations). As shown in FIG. 5, conventionally, an input / output device 61 which is a slave station is used.
And the PLC 51 as a master station are connected in a 1: n connection mode. The data input by the input / output device 61 is transmitted to the PLC 51 which is the master station. The output data is transmitted from the master station PLC 51 to the input / output device 61, and the input / output device 61 that has received the data outputs the data.

[0003]

However, in the above-mentioned prior art, when it is desired to perform input / output from the PLCs 52 and 53 other than the master station, the data is once transmitted to the master station PLC 51 via another network 70. To transmit and output the data from the master station PLC 51 to the input / output device 61,
Further, the master station PLC 51 needs to receive the input data received from the input / output device 61 via another network 70. As a result, extra PLC processing is required to perform input / output, resulting in a long input / output time. On the other hand, Japanese Patent Application Laid-Open No. 8-202409 discloses a process control device having a plurality of control target devices.
There is disclosed a distributed control device in which a controller that issues a control command to a control target device is installed on site in accordance with each control target device. For input / output devices, a bus-connected CP is disclosed.
In the U and the input / output device, a switch circuit is provided for each input / output device between the input / output bus address from the CPU to the input / output device and the actual input / output contact. The content has been made available. However, the above-mentioned JP-A-8-20240
In the device disclosed in Japanese Patent Application Laid-Open No. 9-205, the connection between the address decode result on the input / output bus and the input / output contact is simply switched by a hardware switch circuit, and only in a distributed control device having the input / output device. There was a problem that I / O data could not be handled. Therefore, an object of the present invention is to provide means for sharing a distributed input / output device connected through a communication line with a plurality of distributed controllers.

[0004]

In order to achieve the above object, the present invention provides a plurality of input / output devices connected to a plurality of programmable controllers via a network, wherein each input / output device is provided with input / output data. , And each programmable controller has:
A plurality of programmable controllers on the network for a single input / output device, having a second link buffer corresponding to each of the input / output devices, and a unit for transmitting output data at regular intervals; It was made accessible from.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as shown in FIG. 1, an input / output device 11 and a plurality of PLCs 1 to 4 are connected to a network 20 in an n-to-n connection mode. By broadcasting to a plurality of PLCs 1 to 4 on the network 20, input data of one input / output device (for example, the input / output device 1) can be referred to by all the PLCs 1 to 4 on the network 20.
The input / output device 11 has buffers (first link buffers) 31, 32, 33 for storing input / output data, and the first link buffers 31, 32, 33
4 for each station number. Each PLC1
4 transmit output data to the input / output device 11, and upon receiving the data, the input / output device 11 stores the received data in the first link buffer corresponding to the station number. The output of the data is performed based on the correspondence table between the data of the first link buffer and the output module. Thus, each of the PLCs 1 to 4 can transmit output data to the input / output device 11. According to the above-described means, one input / output device can be shared by a plurality of PLCs, and there is no need to exchange input / output data with one PLC unlike the related art, so that the processing time can be reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram of the system. First, the PLCs 1, 2,... On the network have input / output data buffers 41, 42, 43 as shown in FIG. These buffers 41, 42, and 43 are called second link buffers. The second link buffer is subdivided for each partner station. Each PLC transmits output data for each PLC scan cycle. Also, the input / output device 11 has a PL
First link buffers 31, 32, 33 similar to C1 to C4
The output data transmitted by each PLC is received and stored in the first link buffers 31, 32, and 33. I / O device 1
As shown in Table 1, No. 1 has a correspondence table indicating which data of the first link buffer is output to which module, and which module input data is stored in which first link buffer.

[0007]

[Table 1]

[0008] Input data from the PLC 1 is stored in a first link buffer 31, and data from the PLC 2 is stored in a first link buffer 32. The data in the first link buffer 33 is broadcast to the PLC on the network at a fixed cycle. Each PLC can refer to input data from the input / output device at the same timing. In the system shown in FIG. 2, when one word data is output from the PLC 1 to the module M1 of the input / output device, when one word data is output from the PLC 2 to the module M2 of the input / output device, Let us consider a case in which input data from the module M3 is input to the PLCs 1 and 2. The data of the PLC1 and the data of the PLC2 are transmitted at the scanning cycle of each PLC. The transmitted data is received by the I / O device, and the first of the I / O device
The data is stored in an area allocated to each PLC in the link buffer.

As shown in FIG. 4, the input / output device 11 performs input / output processing based on a correspondence table set by a user. The input / output device 11 firstly receives the first link buffer 31
Out of the data from the PLC 1 stored in the
Is output as one word to the module M1. Next, the PL stored in the first link buffer 32
Among the data from C2, one word of data at the address IW200 is output to module M2. Finally, the one-word data input from the module M3 is stored in the first link buffer 33 at the address OW300.
The data in the first link buffer 33 is broadcast to all PLCs on the network after the input / output processing is completed. The broadcast data is PLC1, P
The data is received by the LC2 and stored in the area of each of the first link buffers allocated to the reception from the input / output device. The stored data is decoded by the ladder processing of the PLC.

[0010]

As described above, according to the present invention, each input / output device has a first link buffer for storing input / output data, and each programmable controller has a second link buffer corresponding to each input / output device. By having a buffer and a means for transmitting output data at regular intervals, one input / output device can be shared by a plurality of PLCs, and input / output processing can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an input / output device and a PLC according to the present invention.

FIG. 2 is a system configuration diagram of an embodiment.

FIG. 3 is a diagram showing a first link buffer.

FIG. 4 is a diagram showing a data structure inside an input / output device.

FIG. 5 is an input / output device according to the related art.

[Explanation of symbols]

1-4 PLC, 11 PLC (programmable controller), 20 networks, 31-34 first link buffer, 41-43 second link buffer, M1-
M3 module

Claims (1)

[Claims] 1. A plurality of input / output devices connected to a plurality of programmable controllers using a network, wherein each input / output device has a first link buffer for storing input / output data, and each programmable controller has ,
A plurality of programmable controllers on the network for a single input / output device, having a second link buffer corresponding to each of the input / output devices, and a unit for transmitting output data at regular intervals; An input / output device characterized in that it can be accessed from a computer.