Remote Program Mode

[OhioAviator]

Has anyone ever heard of an Allen-Bradley SLC 5/05 processor putting 'itself' into Remote Program Mode?

As far as I know, the only two ways to put the processor into Remote Program mode is to (a) connect to the processor with RSLogix and switch modes that way, or (b) turn the processor keyswitch from REM to PROG and then back to REM.

Before I go accusing someone of getting into the PLC cabinet, is there a bug in the SLC 5/05 processor that I'm not aware of?

Thanks,

--JR

 

[jonesy29847]

A program error may also place the processor in the remote program mode. I had an issue with a processor going into an error mode when a counter reached a certain value because I was using the accumulated vale as an index and did not have quite enough memory allocated. When I reset the PLC the conditions causing the increment were no longer true.

 

[nedrapp]

Writing to the status registers can also do this. If you are using indexed or offset output instructions to the status registers, you may be shooting yourself in the foot.

 

[OhioAviator]

Thanks for your suggestions, they're very much appreciated.
So far, we haven't been able to duplicate the problem. We aren't writing to the status registers at all, so that possibility is eliminated. And we haven't really had any program errors after commissioning (6 months ago).

Methinks we're back to keeping the plc cabinet locked to keep unauthorized persons out.

Thanks again,

--J.R.