JPS61278237A - Data transmission system of process control system - Google Patents

Abstract

PURPOSE:To attain data transfer between process controllers by providing a repeater storing tentatively a transfer data between controllers and adding information of a transfer path to the transmission data. CONSTITUTION:In sending a data from a PC 6 to a PC 3, the number of repeaters 7, 8 existing in the path from the PC 6 to the PC 3 and the number of the PC 3 being the final object are generated and stored tentatively as a forward path header. A sending data is stored in a 2-port RAM 10 by a CPU 12 of the repeater 8 and read by a CPU 11. When the CPU 11 discriminates that the next destination is the repeater 7, the number of the repeater 8 in the forward path header into the lowest priority and selects the number #7 of the repeater 7 as the highest priority newly. When the repeater 7 receives the data from the repeater 8, the similar processing as that of the repeater 8 is executed and the data from the PC 6 is sent to the PC 3. In sending the transmission data from the PC 3 to the PC 6, the transfer path is selected according to the content of the return header.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a data transmission method for a process control system.

B. Summary of the Invention The present invention provides a process control system in which a plurality of process control devices 1 are connected in a hierarchical manner, in which a repeater is provided between process control devices at different hierarchical levels to temporarily store data transferred between these devices. The present invention is intended to enable data transfer between process control devices without requiring complex data exchange functions to be provided to relays, repeaters, and process control devices.

BACKGROUND OF THE INVENTION Conventionally, there has been a system in which a plurality of process control apparatuses are connected in a hierarchical manner to form a network of process control apparatuses.

In such a system, each process control device (hereinafter abbreviated as PC) is assigned to each one and performs ratio control independently, but if necessary, PLCs at other hierarchical levels can be used.
Data may be transferred to C.

D1 The problem that the invention aims to solve However, in the conventional system, the PCK of other hierarchical levels
When transferring data, it was configured to add only the information of the intended transfer destination to the transmitted data and send it, so it was necessary to install a relay between each hierarchical level or a complicated data conversion function for each PCVC. The problem with this is that it doesn't have to be.

An object of the present invention is to provide a data transmission method for a process control system that enables data transfer between each 20 units with a simple configuration without requiring a repeater or each PC to have a complicated data exchange function. .

Means for Solving All E1 Problems The present invention provides a relay between process control devices at different hierarchical levels to temporarily store data transferred between these devices.
When each process control device transfers data to a process control device at a hierarchical level different from the one to which it belongs, it is necessary to Adding the number of the process control device to be sent and its own number to the transmission data and transmitting it via the repeater, and the repeater receiving the transmission data determines the next destination based on the information of each number, The received data is sent to the destination.

F. The next data transmitted from an active source is temporarily stored in a repeater connected to the source. Thereafter, the transfer destination is determined by the relay device, and then the message is transmitted to the next transfer destination, and finally received by the target PC.

G. Example Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a block diagram showing an embodiment of a system to which the present invention is applied. This embodiment has two hierarchical levels, L and L! The pass line BUS and Ki/120 PC1 and 2 of level L are connected. In addition, each lower level LtVC is independent and friend 2
Two pass lines BUS, , BUSs i: are provided, and each pass line has two PCs 6, 4 and 5, respectively.
．． 6 are combined. Furthermore, between the pass line BUS of each level and BUS2, and between BUSI and BUS,
A repeater 7.8 for relaying data transfer is connected between the two terminals.

As shown in FIG. 2, the repeaters 7 and 8 have two data input/output terminals, and a CPU connected to each data input/output terminal.
2 that can be accessed in a time-sharing manner from 11 and CPU 12
It also has a memory 13, 14 in which read/write control logs 2, etc. are stored, and a transmission interface 15, 16 with a PC.

Here, it is assumed that the numbers of PCs and repeaters are determined as shown in the following table.

In Table 1, for example, when data is transferred from PC6 to PC3, as shown in FIG. 3(a), the source PC6
The number of the destination PC3 is known as the source address SAD, and the number of the destination PC3 is the destination address DAD.
The memory (not shown) is stored in the NC. Also, the numbers of repeaters 7 and 80 existing on the route from PC6 to PC4 and the number of the final destination PC3 are generated in the same way and temporarily stored as the outgoing route header. In addition, the memory in the PC 6 also has a storage area for a return header indicating the route when receiving reply data from the PC 3, and a round trip/return control indicating which of each header should be used in the current transfer operation. A storage area is prepared for temporarily storing information and information indicating the current hierarchy level.In this case, when the round trip/return control information is "1", it instructs that the information in the forward route header should be used, When it is "0", it indicates that the information in the return path header should be used.In addition, the information indicating the hierarchy level is "1" when the current progress position of the transfer data is within hierarchy level L, and when it is within Lt. In some cases, it is "2".Furthermore, the numbers in the 1 outbound header are sequentially assigned to the PC from the first transfer destination.
6 is stored in memory. Further, the number in the return head is added to indicate the route of the return data by a repeater in the middle of the route after the transmission data has been sent to the PC 6 as the transmission source. Therefore, when transmitting data from the PC 6, the source address SAD, destination address DAD
, an outbound header, forward/return control information, and layer level information are added to the data to be transferred and transmitted.

This transmission data is stored in the 2-baud 1-RAM 10 by the CPU 12 of the repeater 8. After this, C in repeater 8
When the PU 11 detects that there is transmission data in the RAM 10, the data is read out by the CPU 11, and its transfer destination is determined by referring to the outgoing route header and all nine hierarchical level information of the forward/return control information. When CPtJll determines that the next transfer destination is repeater 7, it replaces the number of repeater 8 in the outgoing route header to the lowest rank, and newly sets the number 7 of repeater 7 to the highest rank. Further, the number reference 8 of the repeater 8 is inserted at the lowest information position of the return route header, and the hierarchical level information is changed to "2" indicating level L. That is, information as shown in FIG. 3(b) is added to the data to be transferred and transmitted from the repeater 8.

When the repeater 7 receives such data from the repeater 8, it executes the same process as the relay "IgI8" and sends the PC6
The data from is sent to PC3. Then, the PC 3 receives the data from the PC 6 and the information for controlling the transfer path thereof, with a configuration as shown in FIG. 3(C). That is, the numbers in the outgoing route header start with the number of PC3 at the top and repeater 7. The order of the numbers of the repeaters 8 is changed and the signals are received.

In addition, in the return header, there is a repeater 7 at the top, and a repeater 8 next. The number of PC6 is added to the lowest position and received.

Therefore, when transmitting reply data from PC 6 to PC 6, the transfer route may be selected according to the contents of the return route header. In order to select the transfer route based on the contents of the return route header, the forward/return control information may be changed from "1" to "O".

The above is a description of the case of transferring from PC6 to PC3, but even for other routes, the transfer route is selected by the same operation and received by the intended destination PC.

Note that PCs at the same hierarchical level (for example, PC5)
Data transfer between the PC 6 and the PC 6 is performed by obtaining the right to use the common bus 2y on a time-sharing basis.

H6 Effects of the Invention As is clear from the above explanation, the present invention adds information about the transfer route to the data to be transmitted and sends it, and the repeater transfers the data to the next destination according to this information. It is only necessary to send data to the network, and there is no need to have a special exchange processing function to determine which route in the network should be passed, making the configuration extremely simple and inexpensive. Further, when a transmission error occurs, by referring to information such as the outgoing path header and the incoming path header, it is possible to extremely easily determine at what stage the error has occurred.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of a repeater, and Fig. 3 shows the transition of information for transfer route control that is added to transmission data and transmitted. FIG. 1 to 6... Process control device, 7.8... Relay device,
10...2 Boat RAM. Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) In a process control system in which multiple process control devices are connected in a hierarchical manner, a repeater is provided between the process control devices at different hierarchical levels to temporarily store data transferred between these devices, and each process control device is self-contained. When transferring data to a process control device at a hierarchy level different from the hierarchy level to which it belongs,
The number of the repeater existing on the path leading to the target process control device, the number of the target process control device, and its own number are added to the transmission data and transmitted via the repeater, and this transmission data A data transmission system for a process control system, in which a repeater that receives received data determines the next destination based on the information of each number, and transmits the received data to the destination. (2) A data transmission system for a process control system according to claim (1), wherein the repeater is configured with a two-port memory. (3) The numbers of repeaters existing on the route to the target process control device are sent in the order of the transmission route from the sender, and the repeater that receives this number is the repeater that has already passed through. Alternatively, the data transmission method for a process control system according to claim 1, wherein the number of the process control device is changed to the lowest order and transmitted to the next destination.