GE Fanuc PLC Communication


Thread Starter


I am using GE Fanuc Versa Max PLC IC200UAL006. When trying to get data from external source (serial data) the error coming in PLC fault table is "Comm req not processed due to PLC memory limitations"
can anybody help me what is the problem.
Pls. treat this as urgent....

To help, I need to ask some questions:
.. what protocol?
.. what command are you sending?
.. how much data are you expecting?
.. what kind of a device is the recipient?

I'm not familiar with that exact error, but it sounds like the commreq data block may be trying to access memory beyond the memory limits of
either the VersaMax OR the target device.

Please contact me off-list if you want to discuss further.

Drake Fink
Application Engineer
GE Fanuc
[email protected]

John Beaudry

You didn't provide enough information to provide a solution, but there are a few things that you should check.

There are several steps to setting up the communications. All commands are executed through the comreq function. The first step is setting up the port as RS-232, SNP, or RTU. All Comreq functions should be one-shot. I would review the manual on serial coms very carefully for each comreq function. The register's used are confusing (sometimes you are pointing directly at a register sometime it is offset, also the number of bytes for the instructions can be misleading).

And of course you should check the memory in the PLC. Have you overloaded the PLC? You can change the sizes of the serial buffers in the
comreq setup function.

Good luck I fought through a fairly complicated rs-232 communication on a VersaMax and I got it working well. Reading the details and
looking at the examples was essential.