JPH09219714A - Transmission control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily control the synchronization of a whole control system by eliminating a delay time in data transmission and the influence of its dispersion and guaranteeing the simultaneity of data without performing complicated processing such as interlock control, etc., through the use of programmable controllers with normal processing speed. SOLUTION: A transmitting station 2 operating as a master station transmits start data to a transmission path 1 at every fixed cycle and also processes the exchange of input/output data with the programmable controllers of the self station 4-0 to 4-n. The other transmitting stations 3-1 to 3-n receive start data and process the exchange of input/output data with the respective programmable controllers 4-0 to 4-n of the self station. The respective transmitting stations 2 and 3-1 to 3-n mutually process the exchange of input/output data within the transmission cycle, the respective programmable controllers 4-0 to 4-n execute the one-scanning of respective control programs after an input/output processing and the control operations of the whole programmable controllers 4-0 to 4-n are synchronizised.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system used in a system for controlling various devices by using a plurality of programmable controllers (hereinafter abbreviated as PCs), and particularly in the case of performing synchronous control between various devices. PC
The present invention relates to a transmission control system for performing data transmission between devices.

[0002]

2. Description of the Related Art A PC controls various devices by updating input / output data by a scan execution method in which a control program is repeatedly executed at high speed. In some cases, these PCs and other control devices are connected to one transmission line via a transmission station and exchange input / output data with each other. In this case, the lower-level device transmits data indicating the operation state of the controlled object, and this data is data directly related to the operation, and when performing the organic control in which the operation timings of the plurality of controlled objects are related to each other, High-speed response and simultaneity of data exchange are required.

Control cycle of each transmission station (transmission cycle)
Since the control cycle of each PC is independent and operates asynchronously, the maximum delay time until the input / output data of the PC of the transmitting station is received by the receiving station is twice the transmission cycle,
The maximum transmission delay time from the PC of the transmitting station to the PC of the receiving station is twice the transmission cycle + the control cycle of the PC on the receiving side. Further, the control cycle of the PC also changes the execution time of one scan of the control program, so that the transmission delay time varies.

When the transmitting station transmits a plurality of data as data of the same group to another station, the data simultaneity is ensured by ensuring that old and new data are not mixed.
When C writes data to the interface section of the transmission station, an interlock is provided to prevent the data processing section from reading the data. Further, at the receiving station, when the data processing section writes data to the interface section, the PC changes to the interface section. An interlock was provided to prevent reading. As a result, there is a possibility that a delay time of 3 times the transmission cycle + twice the control cycle of the PC on the receiving side may occur in the data transmission / reception while guaranteeing the data simultaneity. Therefore, when the operations of various devices are synchronized, the transmission delay time is shortened by using a PC or a transmission device that operates in a faster control cycle, and its variation is reduced.

[0005]

When the control cycles of the PC and the transmission station are asynchronous, the conventional system operates at a higher speed so that the variation of the transmission delay time falls within the control error range as described above. Using a PC or transmission device,
Further, in order to guarantee the simultaneity of data, it is necessary to provide an interlock control in an interface section that transfers and receives data between the PC and the transmission station, which causes a problem such as complicated control.

The present invention has been made in order to solve the above problems, and an object of the present invention is to use a PC having a normal processing speed and to perform data processing without performing complicated processing such as interlock control. An object of the present invention is to provide a transmission control system which eliminates the influence of transmission delay time and its variation, guarantees simultaneity, and can easily perform synchronous control of the entire control system.

[0007]

In order to achieve the above object, a transmission control system according to the present invention has a plurality of transmission stations connected via a transmission line, and each transmission station communicates data with a programmable controller. An interface unit for exchanging data, a transmission / reception unit for exchanging data with other transmission stations, a data processing unit for processing transmission / reception data,
A transmission station that operates as a master station is provided with a media access control unit that controls the transmission / reception unit, sends start data to a transmission path at regular intervals, and exchanges input / output data with its own programmable controller. When the other transmission stations receive the activation data, they perform the processing of exchanging input / output data with the programmable controller of their own station. After exchange, each programmable controller executes one scan of each control program after input / output processing, and synchronizes the control operation of all programmable controllers. (Claim 1) Further, the transmission station operating as a master station sets a timer for determining a transmission timing of the activation data transmitted at regular intervals and a setting of the timer from a programmable controller connected to the transmission station. A unit for changing the fixed period is provided, and the transmission period can be changed. (Claim 2) Furthermore, the transmission station that operates as a master station includes a counter that is incremented for each transmission cycle, adds the value of the counter to the start data, and transmits the data. Program control is performed based on the value to control the start and step of the process, and control and synchronize the operation timing of each controlled object. (Claim 3) Further, the transmission station operating as a master station is provided with means for presetting the counter to a predetermined count value in response to a command from a programmable controller connected to the master station, and is connected to another transmission station. The programmable controller performs program control based on the predetermined count value, controls the start and step of the process, and synchronizes the control operation. (Claim 4) Further, each transmission station performs interrupt input to the programmable controller of its own station via the interface section based on the start data, and performs the input / output processing. (Claim 5) Further, each transmission station performs input / output processing with its own programmable controller, then creates a transmission data frame with the latest input data, and mutually transmits the transmission data frame within the transmission cycle. Give and receive. (Claim 6) Further, when each transmission station performs input / output processing with its own programmable controller, the latest reception data is used as output data. (Claim 7)

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An outline of a transmission control system according to the present invention is shown in FIG. This transmission control system includes a transmission station (master station) 2 and a plurality of transmission stations (slave stations) 3 (-1
...- n) is connected to the transmission line 1, and the PC 4 (-0, -1) that controls the control target not shown in the master station 2 and each slave station 3, respectively.
...- n) are connected and are arranged in a distributed manner based on the arrangement of the controlled objects. A loader 5 is connected to the PC 4-0 connected to the master station 2.

FIG. 2 shows the hardware of the transmission stations 2 and 3 and is an embodiment showing the configuration of the main part of the present invention. As shown in FIG. 2, the master station 2 and each slave station 3 have an interface unit (hereinafter abbreviated as I / F) 6 for exchanging data with a PC 4 connected to the master station 2, and control of the own station. A data processing unit 7 that controls the operation, a media access control unit (hereinafter abbreviated as MAC) 8 that performs a transmission right passing process and a line control, and a transmission / reception unit 9 that exchanges a data frame with the transmission path 1.
The I / F 6 has an interrupt circuit 16 and a dual port memory 13, and the data processing unit 7 has a memory 14 and a CP.
U4, PC4 from CPU15 interrupt circuit 1
Input / output data is transmitted / received via the dual port memory 13 according to an interrupt command input via 6.

The master station 2 is further connected to an internal bus 12 with a timer 10 for generating an activation signal St at a constant cycle T0. An example of the operation of the transmission control system having the above configuration is shown in the timing chart of FIG. CPU 15 of master station 2
When receiving the activation signal St generated at the constant period T0 generated by the timer 10, the device reads the activation data stored in the memory 14 and transfers it to the MAC 8, and transmits it to the transmission line 1 via the transmission / reception unit 9 as activation transmission. At the same time as sending (broadcast sending), a start signal St is sent to the interrupt circuit 16, and PC4 (-
Upon receiving this, 0) performs input / output processing. That is, PC
4 (-0) receives the interrupt input by the start signal St,
Input / output data is exchanged with the dual port memory 13, and the CPU 15 stores the updated latest data of the dual port memory 13 in the memory 14.

On the other hand, each slave station 3 (-1 ...- n) receives the activation data transmitted from the master station 2 at the transmitting / receiving unit 9,
When the data is transferred to the data processing unit 7 via the MAC 8 and the CPU 15 determines that it is activation data, it transmits an activation signal to the interrupt circuit 16 and inputs it to the PC 4 (-1 ...
-n) performs the input / output processing in the same manner as described above, and stores the latest data in the memory 14 of each slave station 3 (-1 ...- n).

All PCs 4 (-0,
-1 ...- n) executes the user program (control program) stored therein for one scan only, and waits until the next start signal. Further, the data processing units 7 of all the transmission stations 2 and 3 that have completed the input / output processing read the latest data of the preset area to be transmitted from the memory 14 and create a transmission data frame.

Following the input / output processing, the master station 2 sends a transmission data frame to the transmission path 1 via the MAC 8 and the transmission / reception circuit 9 (broadcast transmission), and each slave station 3 (-1 ...- n) transmits / receives data. This is received at 9, the data frame received at the MAC 8 is interpreted and sent to the data processing unit 7, and the latest data transmitted from the master station is stored in the memory 14. When the master station 2 finishes transmitting the transmission data frame, the master station 2 transfers the transmission right to the slave station 3 and enters the reception state.

The slave station 3 which has acquired the transmission right transmits the latest data stored in the memory 14 to be transmitted by itself to the transmission line 1 via the MAC 8 and the transmission / reception circuit 9 (broadcast transmission), and the master station 2 And other slave stations 3 respectively receive the transmission data and store it in the memory 14. The slave station 3 that has completed the transmission becomes the receiving state and sequentially transfers the transmission right to the other slave stations 3, and all slave stations 3
When the transmission right is distributed to the master station 2, it is returned to the master station 2 and the transmission right makes a round, and the transmission of one cycle is completed. The master station 2 has a fixed period T0
After that, the start signal is transmitted again by the start signal St, the above-mentioned operation is repeated, each transmission station exchanges input / output data with each other within the transmission cycle, and each PC executes the scan of the control program in synchronization with the transmission cycle. I do. FIG. 3 shows an example in which the transmission right is transferred from the parent station 2 to the child station 3-1 and the transmission right goes around in the child station 3-n. (Claims 1 to 5) Further, the master station 2 provides the memory 14 with a specific data area that can be changed by the control program of the loader 5 or the PC 4,
During input / output processing, the data in the specific data area is sent to the data processing section 7 via the interface section 6, and the CPU 15
Has a function of changing the period T0 of the start signal St by changing the set value of the timer 10 based on the data, and the minimum transmission period required for all transmission stations to exchange input / output data. In the above range, the transmission cycle T0 can be freely changed. As a result, the processing speed of the entire control system can be freely changed within the range of a predetermined processing speed or less. (Claim 2) Further, the master station 2 is incremented every fixed period T0, and when it exceeds a predetermined value, it is cleared to 0 and starts counting again, and the counter 11 which operates as a ring counter is connected to the internal bus 12. The CPU 15 reads the current value of the counter 11 and adds the current value of the counter 11 to the start data stored in the memory 14 at the time of start transmission to perform start transmission. At each slave station 3, the received current value of the counter 11 is stored in the memory. 14 and sends it to the PC 4 via the dual port memory 13 at the time of input / output processing.
The control program operates based on the current value of 1 to control the start and step of the process and synchronize the control operation. (Claim 3) Further, the master station 2 provides the memory 14 with a specific data area that can be changed by the control program of the loader 5 or the PC 4.
During input / output processing, the data in the specific data area is sent to the data processing section 7 via the interface section 6, and the CPU 15
By changing the value of the counter 11 to a predetermined count value based on the data, the PC connected to the master station 2
A predetermined control of each PC 4 (-1 ...- n) is started by the control program 4-0, the start of the process and the step are controlled, and the control operation is synchronized. (Claim 4) Since the present value of the counter 11 is incremented every transmission cycle, it can be used as synchronization control or transmission confirmation data.

[0015]

According to the transmission control system of the present invention, a PC having a normal processing speed is used, without performing complicated processing such as interlock control and eliminating the influence of variations due to the transmission delay time of data. It is possible to provide a transmission control system which can guarantee the simultaneity of the above and easily synchronize the control operation of the entire control system.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a transmission control system according to the present invention.

FIG. 2 is a configuration diagram of a transmission station in the above embodiment.

FIG. 3 is a timing chart for explaining the operation of the above embodiment.

[Explanation of symbols]

1 ... Transmission path 2 ... Transmission station (parent station) 3 ... Transmission station (slave station) 4 ... Programmable controller 5 ... Loader 6 ... Interface unit 7 ... Data processing unit 8 ... Media access control unit 9 ... Transmission / reception circuit 10 ... Timer 11 ... Counter 12 ... Bus 13 ... Dual port memory 14 ... Memory 15 ... CPU 16 ... Interrupt circuit

Claims (7)

[Claims] 1. A plurality of transmission stations are connected via a transmission line,
Each transmission station has an interface section for exchanging data with the programmable controller, a transmission / reception section for exchanging data with other transmission stations, a data processing section for processing transmission / reception data, and the transmission / reception section. The transmission station, which has a media access control unit that controls the control unit, sends the startup data to the transmission path at regular intervals and exchanges input / output data with its own programmable controller. When the other transmission stations receive the activation data, they perform the process of exchanging input / output data with the programmable controller of their own station, and each transmission station exchanges the input / output data with each other within the transmission cycle. , Each programmable controller executes one scan of each control program after input / output processing, Transmission control system characterized by synchronizing the control operation of the roller. 2. The transmission control system according to claim 1, wherein the transmission station that operates as a master station is connected to the transmission station and a timer that determines the transmission timing of the activation data transmitted at regular intervals. A transmission control system, comprising means for changing the setting of the timer from the programmable controller to change the fixed cycle, and enabling the change of the transmission cycle. 3. The transmission control system according to claim 1, wherein the transmission station that operates as a master station includes a counter that is incremented every transmission cycle, and the value of the counter is added to the start-up data for transmission. Then, each programmable controller performs program control based on the value of the counter, controls the start and step of the process, and synchronizes the control operation. 4. The transmission control system according to claim 3, wherein the transmission station operating as a master station has means for presetting the counter to a predetermined count value in response to a command from a programmable controller connected to the transmission station. A transmission control system comprising: a programmable controller connected to another transmission station, performing program control based on the predetermined count value, controlling the start and step of a process, and synchronizing the control operation. 5. The transmission control system according to claim 1, wherein each transmission station performs interrupt input to a programmable controller of its own station via an interface section based on the start data to perform the input / output processing. Characterized transmission control system. 6. The transmission control system according to claim 5, wherein each transmission station performs input / output processing with its own programmable controller and then creates a transmission data frame with the latest input data. A transmission control system, wherein transmission data frames are exchanged with each other within the transmission cycle. 7. The transmission control system according to claim 6, wherein each transmission station uses the latest received data as output data when performing input / output processing with its own programmable controller. Transmission control system.