SVC instruction help....

Quick question on the SVC (Service Communication) instruction for the SLC family of processors.

When you add this instruction into your PLC program, do you need to have an instruction that goes true and false to the left on the same run where the SVC output is located.

I added one on a program but I didn't put another instruction to the left of the SVC. I just put it separately on one run to execute on every scan and service the communication channels.

No,your choice. See picture.

Thank you Mickey. Any reason why anyone will chose to condition the execution of the SVC instruction?

JoseM said:

Thank you Mickey. Any reason why anyone will chose to condition the execution of the SVC instruction?

Click to expand...

Scan time issues?

The Instruction Help in RSLogix500 for the SVC instruction has a link to an example where the SVC is triggered conditionally on a rung.

In the example, an SVC is executed when a message (MSG) instruction has been enabled. The SVC causes the communications to occur before the end of the program scan.

This, of course, will have an impact on the scan time.