Control system, control apparatus and control method with input-only communication frame
A control system includes a master apparatus that includes a calculation unit and a communication processing unit, and one or more slave apparatuses connected to the master apparatus via a network. The communication processing unit is configured to manage cyclic transmission, on the network, of a data sequence containing data that is handled by the master apparatus and the one or more slave apparatuses. The communication processing unit is configured to start cyclic transmission of a first data sequence that contains output data for the one or more slave apparatuses in conjunction with execution of output processing in the operation unit, and to start, a predetermined time period before execution start of input processing in the operation unit, cyclic transmission of a second data sequence for obtaining information collected by the one or more slave apparatuses from the control target.
1. A control system for controlling a control target, comprising:
a master apparatus comprising:
a processor configured with a program to perform operations comprising:
operation as a calculation unit; and
operation as a communication processing unit; and
one or more slave apparatuses connected to the master apparatus via a network, wherein:
the processor is configured with the program to perform operations such that operation as the calculation unit comprises operation as the calculation unit configured to repeatedly execute, in a predetermined execution cycle, operations comprising:
output processing comprising generating output data comprising an execution result of a user program;
input processing comprising updating input data in the master apparatus according to information collected from the control target by one or more of the slave apparatuses; and
execution of the user program during a time period in which the output processing and the input processing are not executed; and
the processor is configured with the program to perform operations such that operation as the communication processing unit comprises operation as the communication processing unit configured:
to start cyclic transmission of a first data sequence comprising the output data for the one or more slave apparatuses after the execution of the output processing such that the cyclic transmission of the first data sequence occurs concurrently with at least one of: the input processing; and the execution of the user program; and
to start cyclic transmission of a second data sequence for obtaining information collected by the one or more slave apparatuses from the control target such that the cyclic transmission of the second data sequence completes before the input processing of a next execution cycle and the cyclic transmission of the second data sequence occurs concurrently with at least one of: the output processing;
and the execution of the user program.
2. The control system according to claim 1 , wherein
the processor is configured with the program to perform operations such that operation as the communication processing unit comprises operation as the communication processing unit configured to, after the cyclic transmission of the first data sequence is started, start the cyclic transmission of the second data sequence, independently from arrival of the first data sequence at the master apparatus after the cyclic transmission of the first data sequence.
3. The control system according to claim 1 , wherein
the first data sequence and the second data sequence comprise a same data structure.
4. The control system according to claim 1 , wherein
both the first data sequence and the second data sequence comprise a command for obtaining information from the one or more slave apparatuses and the output data.
5. The control system according to claim 4 , wherein
the output data contained in the second data sequence is invalidated.
6. The control system according to claim 4 , wherein
each of the one or more slave apparatuses is configured to discard the output data contained in the second data sequence.
7. The control system according to claim 1 , wherein
the processor is configured with the program to perform operations comprising determining a time at which the cyclic transmission of the second data sequence is started based on an offset value using a time at which the input processing is started as a reference.
8. The control system according to claim 7 , wherein
the processor is configured with the program to determine the offset value based on an initial configuration result of the network.
9. A control apparatus for controlling a control target, comprising a processor configured with a program to perform operations comprising:
operation as a calculation unit; and
operation as a communication processing unit coupled to the calculation unit, wherein:
the control apparatus is connected to one or more slave apparatuses via a network;
the processor is configured with the program to perform operations such that operation as the calculation unit comprises operation as the calculation unit configured to repeatedly execute, in a predetermined execution cycle, operations comprising:
output processing comprising generating output data comprising an execution result of a user program;
input processing comprising updating input data in the control apparatus according to information collected from the control target by the one or more slave apparatuses; and
execution of the user program during a time period in which the output processing and the input processing are not executed; and
the processor is configured with the program to perform operations such that operation as the communication processing unit comprises operation as the communication processing unit configured:
to start cyclic transmission of a first data sequence comprising the output data for the one or more slave apparatuses after the execution of the output processing such that the cyclic transmission of the first data sequence occurs concurrently with at least one of: the input processing; and the execution of the user program; and
to start cyclic transmission of a second data sequence for obtaining information collected by the one or more slave apparatuses from the control target such that the cyclic transmission of the second data sequence completes before the input processing of a next execution cycle and the cyclic transmission of the second data sequence occurs concurrently with at least one of: the output processing; and the execution of the user program.
10. A control method in a control apparatus for controlling a control target, wherein the control apparatus is connected to one or more slave apparatuses via a network,
the method comprising:
repeatedly executing, in a predetermined execution cycle, output processing comprising generating output data comprising an execution result of a user program;
repeatedly executing, in the predetermined execution cycle input processing comprising updating input data in the control apparatus according to information collected from the control target by one or more of the slave apparatuses; and
repeatedly executing, in the predetermined execution cycle, the user program during a time period in which the output processing and the input processing are not executed;
starting cyclic transmission of a first data sequence comprising the output data for the one or more slave apparatuses after the execution of the output processing such that the cyclic transmission of the first data sequence occurs concurrently with at least one of: the input processing; and the execution of the user program; and
starting cyclic transmission of a second data sequence for obtaining information collected by the one or more slave apparatuses from the control target such that the cyclic transmission of the second data sequence completes before the input processing of a next execution cycle and the cyclic transmission of the second data sequence occurs concurrently with at least one of: the output processing; and the execution of the user program.
11. The method according to claim 10 , wherein after the cyclic transmission of the first data sequence is started, the cyclic transmission of the second data sequence is started, independently from arrival of the first data sequence to the control apparatus after the cyclic transmission of the first data sequence.
12. The method according to claim 10 , wherein both the first data sequence and the second data sequence comprise a same data structure.
13. The method according to claim 10 , wherein both the first data sequence and the second data sequence comprise a command for obtaining information from the one or more slave apparatuses and the output data.
14. The method according to claim 13 , wherein the output data contained in the second data sequence is invalidated.
15. The method according to claim 13 , wherein each of the one or more slave apparatuses is configured to discard the output data contained in the second data sequence.
16. The method according to claim 10 , further comprising determining a time at which the cyclic transmission of the second data sequence is started based on an offset value using a time at which the input processing is started as a reference.
17. The method according to claim 16 , wherein the offset value is determined based on an initial configuration result of the network.