X8 Instruction Set Reference Manual
22-2
Communications Instructions
The following table shows communication instructions of the X8 Series PLC.
SVC - Service
Communication
Instruction Type:
output
Under normal PLC ladder program operation the controller processes
communications once every time it scans the control program. if the ladder
scan is long, it can cause problems in the overall system performance under
the situation that communication is done in the shortest time. The relatively
time-consuming serial communication also can cause problems in the PLC
performance since the timer interrupt service routine will need a lot of time on
communications.
To solve th
e
ses problems, you can use the SVC instruction.
That is, The SVC instruction is used to improve communications performance
and throughput, but also causes the ladder scan to be longer.
The input parameters are:
• Channel Select : serial port number ( 0:COM1, 1:COM2, 2:USB)
If you execute the SVC instruction for 2 or more ports at the same time,
logically ORed 3 ports and then substitute them.
The following is an example of the SVC instruction.
Instruction
Description
SVC
Interrupt the program scan to execute the service
communications part of the operating cycle. The scan then
resumes at the instruction following the SVC instruction.
MSG
Transfer data from one device to another.
Channel Select
Channel(s) Serviced
1h(0 bit)
Serial Channel 0
2h(1 bit)
Serial Channel 1
4h(2 bit)
Serial Channel 2(USB)
8h(3 bit)
Ethernet Channel 3
SVC
EN
ENO
Channel Select
0002h -
Summary of Contents for X8 Series
Page 1: ...Catalog Number s X8 M14DDT X8 M16DDR X8 M32DDT X8 Instruction Manual Reference Manual ...
Page 16: ......
Page 64: ...X8 Instruction Set Reference Manual 2 12 X8 Series PLC Memory and Data Table ...
Page 166: ...X8 Instruction Set Reference Manual 7 8 Relay Type Bit Instructions ...
Page 180: ...X8 Instruction Set Reference Manual 8 14 Timer and Counter Instructions ...
Page 205: ...X8 Instruction Set Reference Manual Math Instructions 10 17 ...
Page 206: ...X8 Instruction Set Reference Manual 10 18 Math Instructions ...
Page 212: ...X8 Instruction Set Reference Manual 11 6 Converion Instructions ...
Page 218: ...X8 Instruction Set Reference Manual 12 6 Logical Instructions ...
Page 236: ...X8 Instruction Set Reference Manual 15 8 Shift and FIFO LIFO Instructions ...
Page 242: ...X8 Instruction Set Reference Manual 16 6 Sequencing Instructions ...
Page 252: ...X8 Instruction Set Reference Manual 18 4 Input and Output Instructions ...
Page 280: ...X8 Instruction Set Reference Manual 20 12 PID Control ...
Page 296: ...X8 Instruction Set Reference Manual 21 16 ASCII Instructions ...
Page 308: ...X8 Instruction Set Reference Manual 22 12 Communications Instructions ...
Page 312: ...Appendix A 4 System Error Code ...
Page 313: ...Appendix B MSG Instruction Error Code MSG Instruction Error Code ...
Page 322: ...Appendix B 10 MSG Instruction Error Code ...
Page 325: ...ASCII Character Set Appendix C 3 ...
Page 326: ...Publication number X8 RM001A EN September 2012 ...
Page 327: ...Copyright 2012 RS Automation Co Ltd All rights reserved ...