JPH0526201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a control system for operating sequencers in parallel.

Conventional technology In conventional small sequencers, the number of control input/output points for controlled devices is large, and when controlling multiple controlled devices because one device is not enough, for example, limit switch signal X1 of the controlled device can be controlled by an internal program. If a sequencer is used, the limit switch signal X1 must be connected to the three input terminals of the sequencer. Furthermore, if the calculation results of one sequencer are to be used by another sequencer, the calculation results must be output to an output terminal, and that output terminal must be connected to the input terminal of the sequencer that requires the calculation results.

As described above, when a single piece of equipment is operated using a plurality of conventional small sequencers, there is a problem in that input and output usage efficiency becomes poor and scalability is lacking.

On the other hand, when controlling equipment with a single large sequencer, there are disadvantages in that if the control part breaks down, the entire equipment goes down, and the input/output signal lines to limit switches, solenoid valves, etc. must be pulled to one location. There must be. In addition, since it is large, it has disadvantages such as requiring a large installation space.

OBJECTIVES Therefore, an object of the present invention is to provide a control system that can shorten the wiring distance of input/output signal lines, increase reliability, and has high efficiency in input/output use and is rich in expandability. .

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. As shown in Figure 1, this control system consists of an optical signal output section OUT that converts serial data into an optical signal and sends it to the optical fiber OF, which is a serial data transmission path, and a serial It consists of a plurality of sequencers PC1 to PCn each having an optical signal input section IN that converts data into an electrical signal. The sequencers PC1 to PCn are connected in a ring through the optical fiber OF. And each of the sequencers PC1 to PCn is
The internal control data memory has control data areas for sequencers PC1 to PCn as shown in Figure 2, corresponding to the number that can be connected to the serial data transmission system.
During actual operation, as shown in FIG. 3, the steps of execution of a user program, output of calculation results, input signal capture, transmission and reception of control data from each sequencer PC1 to PCn are repeated endlessly.
In this case, the control data means each sequencer PC1
- Refers to the signals used in the user's sequence program, such as PCn input signals and output signal numerical data.

Specifically, as shown in FIGS. 4 and 4A, each of the sequencers PC1 to PCn includes (a) an optical signal input section IN, an optical signal output section OUT, a sequencer control section SC, and an input signal conversion section. section CVI, output signal conversion section CVO, and a data bus connecting these,
Sequencer basic unit U1 including read signal lines, write signal lines, etc., and (b) input signal conversion section
It consists of a sequencer basic unit U1, which consists of a CVI' and an output signal converter CVO', and a sequencer input/output expansion unit U2 placed close to it.Although there is only one sequencer input/output expansion unit U2 in the figure, it is possible to connect multiple sequencer input/output expansion units U2. It is possible. The optical signal input section IN and the optical signal output section OUT are as described above.

The sequencer control unit SC receives a serial data input signal from the optical signal input unit IN, outputs a serial data output signal to the optical signal output unit OUT, and also outputs a serial data output signal to the optical signal output unit OUT, as shown in FIG. 4A. A control data memory unit 2 shown in FIG. 4A is used for storing and transmitting control data of each of the sequencers PC1 to PCn shown in FIG. has
Exchange of control data with other sequencers, input signal converter CVI′, CVI′, output signal converter CVO,
Controls data exchange with CVO′.

The input signal converters CVI and CVI' convert multiple signals from external control devices located close to each other into internal IC signal levels and convert them into parallel data buses DB using read signals RD and RD' from the sequencer control unit SC.
Outputs signals from external control equipment on the top.

The output signal conversion unit CVO is the sequencer control unit SC
The contents on the parallel data bus DB are stored using the write signals WT and WT' from the IC, and the signal contents at the IC signal level are converted to a level that can control the loads of external control equipment to control multiple external loads.

To give a supplementary explanation based on FIG. 4A, the serial/parallel converter 3 is a unit that converts a serial electrical signal output from the optical signal input section IN into a parallel signal. The parallel data that has entered this serial/parallel converter 3 is transferred to the control unit.
The message is read by the SC, and the control unit SC processes the message sent. The control operation will be described later. In the parallel/serial converter 4, when there is a message to be sent to the outside, the switch 5 first connects the parallel/serial converter 4 to the optical signal output section OUT by a switching signal via the line 6, and converts the parallel data. By writing in the parallel/serial converter 4, the transmission data is sent out from the optical signal output section OUT. Thereafter, the changeover switch 5 is turned to the Rx' side by a changeover signal from the line 6. The mechanism and operation of the changeover switch 5 will be described later.

Line 7 is a data bus, line 8 is a transmission/reception signal control bus, reference numeral 9 is a read signal,
This is a bus for transmitting write signals, control signals, address signals, etc., and signals for controlling the programmer are derived from line 10. The control data memory unit 2 has a storage area 2a for data transmission.
and an area 2b for storing user programs.
It has an area 2c for storing input/output data.
In the input/output data storage area 2c, the sequencer
Control data for PC1 to PCn is stored respectively. Reference mark RD in the figure indicates a read signal, and WT indicates a write signal.

Next, the operation of this control system is shown in Figure 5A.
An example of sequence control as shown in B will be explained. The program shown in FIG. 5A is inserted into the sequencer PC1 shown in FIG. Then, put the program shown in Figure 5B into the sequencer PC2, and connect the input signal X200 and output signals Y201, Y202 to external equipment via the input signal converter CV1 and output signal converter CVO shown in Figure 4. There is. In this example, each sequencer
Although PC1 to PCn are machine numbers in the 100s, machine numbers in the 1000s and higher order may be used in other embodiments, and the 100s may be set to 0 as input/output data within the own machine. You may set the machine number in the 100s only when using a sequencer.

In this state, when operating as shown in Figure 3,
At timing T3 in Fig. 3, sequencer PC1,
The PC 2 takes in signals from external devices from each input signal converter CVI. Of course, the sequencer
PC1 receives the input signal X110, and the sequencer PC2 receives the input signal X200 from the second controller of the sequencer controller SC.
Write to each control data area shown in the figure.

Next, at timing T4, each sequencer PC
1 to PCn send out their own control data shown in FIG. For example, sequencer PC1 is PC1 in Figure 2.
The memory contents of the control data area (including the input signal 110 data read at timing T3 and the output signal Y101 data calculated at timing T1 and written at timing T2) are converted into optical signals and sent onto the optical fiber OF. send out. At this time,
The other sequencers PC2-PCn write the sent control data of the sequencer PC1 into the PC1 control data area of the control data memory shown in FIG. 2, which each of the sequencers PC2-PCn has.

When the transmission of control data from the sequencer PC1 is completed, the next transmission of control data from the sequencer PC2 begins. In this case, the end of data transmission can be detected by sending an end command at the end of the transmission control data, or by transmitting the number of data to be transmitted before the start of transmission, and each receiving sequencer counts the number of data and transmits the data. There is a way to detect the end of.

In this way, the sequencer PC2 also sends out its own control data from its own control data memory shown in FIG. 2 to the optical fiber OF. At this time,
The other sequencers PC1, PC3 to PCn receive control data (X200,
(including Y201 and Y202).

In this way, the control data transmission of each sequencer PC1 to PCn is performed in order, and when it is completed, the contents of the control data memory of each sequencer shown in FIG. 2 are all the same, and the third timing T1
Each of the sequencers PC1 to PCn executes the user program written in each program memory. When this is completed, the resulting output data is sent to each sequencer at timing T2 in Figure 3.
Write to the output signal converter CVO of PC1 to PCn through the parallel data bus DB to control external equipment.

At this timing T1, FIGS. 5A and 5B
The user program shown in is the programmable controller PC1, PC
It is executed in 2. That is, in the sequencer PC1, the input signal X11 taken in at timing T3
Write 0 to the output signal Y101. sequencer
In PC2, input signal X200 at timing T3
5B using the input signal X110 transmitted at timing T4, the output signal Y101 written by the previous user program execution and transmitted at timing T4, and the input signal X200 fetched at timing T3. The illustrated user program is executed, the AND result of input signals X110 and X200 is written to the output signal Y201, and the output signal 101 of the sequencer PC1 is written to the output signal Y202 of the sequencer PC2.

When the execution of the user program is finished, the output signal is output from the output signal converter CVO to the outside at timing T2 to control the external device. That is,
The sequencer PC1 outputs an output signal Y101 in response to the input signal X110, and the sequencer PC2 outputs an output signal Y201 as an AND result of the input signals X110 and X200, and outputs the output signal Y101 as an output signal Y202.

In this way, by cyclically executing each step as shown in Fig. 3 with the configuration shown in Fig. 1, the user can freely use the input signal and output signal connected to the sequencer PC1 to use the sequencer PC2. It can be incorporated into a program and used. Of course, if timer and counter values and numerical data are also included in the control data and transmitted/received, they can be freely used by other sequencers.

In this embodiment, the control data of the sequencer PC1 was only used by the sequencer PC2, but the reverse is also possible, and the control data of the sequencer PC1 to
In addition to being connected to its own input signal converter CVI and output signal converter CVO, PCn can also freely use the control data of other sequencers written in the control data memory shown in Figure 2 in the user program. It can be used inside the machine, and programs can be created and executed as if it were a single sequencer.

In addition, regarding the control of the transmission system in the system described above, there is an initiative (hereinafter referred to as
This method uses a method in which a token (called a token) is sequentially handed over to sequencers arranged in a ring, and only stations that hold the token can transmit.

Hereinafter, the sequence operation shown in FIG. 3 will be specifically described as a procedure for cyclically performing the sequence execution operation while performing synchronized operation by a plurality of sequencers. Figure 6 shows three sequencers.
An example is shown in which SQ1 to SQ3 are connected.
FIG. 7 shows the state at that time as a time chart. FIG. 8 shows a flowchart of the operation of sequencers SQ1 to SQ3. Each sequencer SQ1~
SQ3 determines whether the current mode is execution mode. If it is not in the execution mode (hereinafter referred to as program mode), repeat the cycle of steps n1, n11, n12, and n1 in the flowchart of FIG.
No sequencer execution operation is performed. In the case of execution mode, it is determined in step n2 whether the execution completion flag is set. The execution completion flag is the user program execution shown in Figure 3.
Operation result output - Set when input signal acquisition is performed. If it is set, the sequencer is in the state shown in FIG. 7, so programmer processing is performed. As a result, the execution completion flag is reset. After this, you will receive a Token. There are cases where the token has already been held, as in the time chart of sequencer SQ2, and there are cases where the token has not arrived even after programmer processing has finished and the token is obtained after passing through the token waiting state, as in sequencer SQ3. There is also.
When the token is returned, the token release process is performed. After this, the sequencer waits for the Token to come around again. Once the Token is returned,
Send the input/output data created earlier in the sequence execution section to all other sequencers. In other words, the message is sent using a so-called global address message whose destination is all addresses. This is indicated by reference numeral 12 in FIG. After this, release the Token.
Furthermore, when I/O transfer is not being performed, it reads I/O data sent from other sequencers and writes the I/O data of the sequencer corresponding to the control data write area shown in FIG. In each sequencer, when the I/O data transfer is completed, it enters a state of waiting for a token. Go again at the same time
It is also in a command waiting state. For example, if ToKen is sent before the GO command is sent (in the case of SQ1 in the example in FIG. 7), this will cause the GO command to be issued to other sequencers. This is the state shown in FIG. At this time, other sequencers execute the user program by receiving the GO command before the Token is held. This is the state shown in FIG. That is, the contents of the user program memory area shown in FIG. 4A are executed. Sequencer SQ1 starts executing the sequence program in response to the GO command issued by itself. This is the state shown in FIG. The subsequent operation continues from step n1 again.

As described above, in this method, multiple sequencers can be synchronized using Token and GO command. In addition, if sequencer SQ1 enters programmer mode in the state shown in Figure 7, that is, in a state where sequencer SQ1 is constantly issuing SO commands, sequencer SQ2
while waiting for a command or token
Since the Token arrives, sequencer SQ2 starts issuing a GO command, and thereafter, the synchronization state is maintained between the plurality of sequencers by the GO command from sequencer SQ2. Also, if there is a sequencer that newly enters synchronous operation, the Token holding state and GO
Depending on the command, for example, if you are in the Token holding state and a GO command has been received, you will know that the Token is being held in the state shown in Figure 7, and if the GO command has not been received, it will be in the state shown in Figure 7.
It can be seen that the token is being held, and synchronized operation can be performed.

In addition, when a programmer connected to one sequencer (see connection example in Figure 6) performs program editing operations such as writing and reading programs to another sequencer, this can be easily done using the data transmission function. be able to. That is, this can be done by sending a message to another sequencer using the Token holding state shown in FIG. This is also possible in the Token holding state shown in FIG.

Further, according to this method, the I/O data transfer time is proportional to the number of connected sequencers in the execution mode, and the smaller the number of sequencers, the shorter the time.

FIG. 9 shows an example of the message format.
The destination address indicates the destination of the message. If you want to send to all, use it as a global address.
Send as FFH etc. The control code defines the role of this message, and in this embodiment, a code is assigned to an I/O transfer frame, a synchronization frame, that is, a GO command, a frame for programmer processing, etc., respectively. The source address indicates the address of the sequencer that sent the message.
The number of data indicates the number of bytes (number of words) of data that is the message body. The data part contains the data of the message body of any length (the number of data is 1).
In the case of bytes, it can be set up to 255 words or less.
The error check code CHK is provided for checking errors in messages, and has a value such as a sum check code written therein.

In this embodiment, the transmission path is an optical fiber, but it may also be configured with an electric wire such as a twisted pair cable or a coaxial cable. When an optical fiber is used as a transmission path, it is not affected by electrical noise such as electromagnetic induction, so data can be transferred reliably between multiple sequencers. In addition, in Fig. 4A, when the signal is not output from Tx' by the changeover switch 5, the changeover switch 5 is connected to Rx', so that the receiving station does not need to transmit data into the loop. However, even without the changeover switch 5, the control unit SC may transmit the received data again at the time of reception.

Effects According to the present invention, a sequencer having a built-in input device and an output device can be placed close to a plurality of controlled devices, so that the wiring distance of input/output signal lines can be shortened.

Furthermore, in the present invention, the entire operation is performed by connecting a desired number of sequencers having the same configuration in a ring, so that it is easy to expand or reduce the scale. Moreover, if one sequencer malfunctions, you only need to replace it.
It is easy to repair and does not completely disable operation.

Each sequencer has a built-in control data memory for storing all the control data of multiple sequencers and a control unit that performs program calculations, stores the input signals and output signals of other sequencers in the control data memory, and has a control data memory for storing all the control data of multiple sequencers. Since input signals and output signals can be treated equally, there is no need for wiring between input and output terminals between multiple sequencers, and input and output usage efficiency is high.

Since a plurality of sequencers are connected through a serial data transmission line made of optical fiber, connection between the sequencers is easy, and the system has excellent noise resistance and high reliability.

Using the Token and GO commands, multiple sequencers synchronously repeat scans consisting of program calculations, output of calculation results, input signal capture, and control data transmission, so each sequencer is identical within the same scan. A user program can be executed based on the data. Therefore, even if a plurality of sequencers are operated in parallel, they can be operated in the same manner as a single sequencer. Furthermore, it can also support programs that assume that control data does not change within one scan, and information such as differential instructions within one scan. Furthermore, when a programmer is connected to a certain sequencer and program editing operations such as program writing and reading are performed, this can be easily done using the synchronized data transmission function.

As described above, according to the present invention, a serial transmission path using a single optical fiber enables synchronous movement between a plurality of sequencers, I/O transfer, and program editing by a programmer between sequencers.

Note that the I/O transfer time only needs to be a time proportional to the number of connected sequencers, and the smaller the number, the shorter the time.

Furthermore, in the present invention, the entire operation is performed by connecting a desired number of sequencers having the same configuration in a ring, so that it is easy to expand or reduce the scale.

Furthermore, when one sequencer malfunctions, only that sequencer needs to be replaced, maintenance is easy, and there is no possibility that all operations will become impossible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the allocation of input/output data in a plurality of sequencers in memory, and FIG. 3 is a diagram showing execution performed during sequencer cycles. Figures 4 and 4a are block diagrams showing the configuration of the sequencer, Figure 5 is a diagram showing how input/output data is used between multiple sequencers, and Figure 6 is a diagram showing the usage of input/output data between multiple sequencers. FIG. 7 is a block diagram showing the connection state, FIG. 7 is a diagram showing synchronous operation by multiple sequencers, FIG. 8 is a flowchart for explaining the operation of the sequencers, and FIG.
The figure shows the format of a message. PC1 to PCn, SQ1, SQ2, SQ3...Sequencer, U1...Sequencer basic unit, U2...
...Sequencer input/output expansion unit, OF...Optical fiber, IN...Optical signal input section, OUT...Optical signal output section.

Claims (1)

[Claims] 1. A plurality of sequencers are connected in a ring through a serial data transmission path made of optical fiber, and each sequencer has an input device for inputting input signals, and an input device for storing all control data of the plurality of sequencers. It includes a control data memory, a control unit that performs program calculations with the input signals, and an output device that outputs the calculation results as output signals, and a programmer that performs editing such as writing and reading sequence programs to the control unit. When a sequencer holds a predetermined Token command, it transfers its own control data, including its own input signals and output signals, to all other sequencers to read them, and then transfers them to the next adjacent sequencer. When the Token command is released and held, the control data transferred from other sequencers is stored in its own control data memory, and the Token command is held again, next:
Generates a predetermined GO command and transfers it to all other sequencers, and the self and all other sequencers perform the program calculations at the same time. After the sequencer that generated this GO command completes the calculation, it transfers the Token command to the adjacent sequencer. Next 1 to do
Transfer it to one sequencer and read it.
The sequencer that holds the Token command will execute the command after the operation is completed if it is in operation, or immediately if it is in an idle state after the operation is completed.
A sequencer control method characterized by giving a Token command to the next adjacent sequencer and repeating such an operation.