Installation manual

Publication 1747-RM001G-EN-P - November 2008
SLC Communication Instructions 12-3
Service Communications
(SVC)
Use an SLC 5/02 Processor
The SVC instruction is an output instruction that has no programming
parameters. When it is evaluated as true, the program scan is interrupted to
execute the service communications part of the operating cycle. The scan then
resumes at the instruction following the SVC instruction. Use this instruction
to enhance the communication performance of your SLC 5/02 processor.
You are not allowed to place an SVC instruction in an STI interrupt, I/O
interrupt, or user fault subroutine.
Use SLC 5/03 and Higher Processors
When using SLC 5/03 and higher processors, the SVC instruction operates as
described above. These processors also allow you to select a specific
communication channel (0, 1, or both) to be serviced. You are not allowed to
place an SVC instruction in a Fault, DII, STI, or I/O Event subroutine.
• SLC 5/03 processor
– channel 0 is RS-232/DF1 Full-duplex, DF1 Half-duplex (master or
slave), DF1 Radio Modem, DH-485, Modbus Remote Terminal Unit
(RTU) Master
(1)
, or ASCII
– channel 1 is DH-485
• SLC 5/04 processor
– channel 0 is RS-232/DF1 Full-duplex, DF1 Half-duplex (master or
slave), DF1 Radio Modem, DH-485, Modbus RTU Master
(1)
, or
ASCII
– channel 1 is DH+
• SLC 5/05 processor
– channel 0 is RS-232/DF1 Full-duplex, DF1 Half-duplex (master or
slave), DF1 Radio Modem, DH-485, Modbus RTU Master
(1)
, or
ASCII
– channel 1 is Ethernet
Output Instruction
Fixed SLC
5/01
SLC
5/02
SLC
5/03
SLC
5/04
SLC
5/05
••••
SVC
SERVICE COMMUNICATIONS
Channel 0
Channel 1
SLC 5/03 and higher
(1)
SLC 5/03, SLC 5/04, SLC 5/05 OS Series C FRN 11 and above