AutomationDirect 450 CPU Lockups

I have an application with an AutomationDirect (KOYO) 450 CPU that communicates to another PLC via leased line modems. I recently moved the communications over from the DCM (data communications) module to port 1 on the 450 and now the PLC locks up solid on a random basis. When it locks up, the "CPU" and "DIAG" lights come on, and the RUN light stays on. The outputs all seem to drop out, and all communications stop, so I can't even access the CPU through the laptop to see what the diagnostic error is. The problem happens anywhere from every few hours to every few days. The port communications are Modbus, 300 baud, odd parity. I tried installing a 'known good' CPU, but the same problem reappeared. The only way to restart the PLC is to cycle the power. The firmware is V1.865. Has anyone had similar problems?

First thing I would do is to update your firmware. It is about three years old. You can find the Koyo firmware update tool here: http://support.automationdirect.com/firmware/index.html. It is listed as Koyo Support Tool.

You will also need the firmware binary file. It can be found here: http://support.automationdirect.com/firmware/binaries.html.

If this does not work, you might want to contact technical support at AutomationDirect. You can email them here: http://support.automationdirect.com/techinquiry.html.

Backplane connections

I recently had an issue where I thought that I was experiencing CPU lock up problems on the 450.
I was told that the backplane can get flakey. Make sure all modules are seated nice.
Also the 'ol battery voltage low problem should not be overlooked. These rigs use a 1.3VDC Lithium.

I recently priced out 450 CPU module repair costs. The high was $340 and the low was $250. Send me message if you want the quote information. I always get three quotes.

I've seen controller memory failures caused by noise and electrical spikes that get in through the RS-232 port. I don't think the Channel 1 on a DL450 is isolated, though the DCM module would have the same isolation as the other I/O modules from the backplane.

B&B Electronics is my favorite vendor for port isolators.

I do not have a manual handy, but I think that the comm module can not be in slot directly to the right of the CPU. Just checking to make sure that is not the problem.