Control Logic Processor

New to RSLogic 5000. Can anybody tell me or point me where I can find out how a control logic processor scans ladder logic? Any help would be greatly appreciated.

The tutorial here would help.

It may be quibbling, but ladders are for display (humans to read), not for storing or scanning by the processor.

Sit down, this could take a while.

ControlLogix has an "execution model" that is a little different from most other PLC's, even other A-B controllers. It's a "preemptive multitasking" system, in which different "Tasks" operate in the controller. These include the Continuous Task, the Motion Task, the Housekeeping Task, and up to 31 different Periodic Tasks or Event Tasks.

It still solves individual ladder logic routines left-to-right, and top-to-bottom. But the way that data is stored, I/O is updated, and routines are scheduled is more complex than an "ordinary PLC" like the SLC-500 or PLC-5.

I strongly recommend the "Logix Controllers Quick Start" document, followed by a stack of instruction set references. You can buy hardcopies from your A-B distributor (there should be a part number for a large stack of manuals for about $100, I think it's 1756-DPALEN) or you can download from:

http://www.ab.com/manuals/cl/

I have, in another thread , already mentioned this preemptive multitasking. I even posted some excerpts from the on-line help.

Kind regards,