Moleller PS416 CPU200

Hi,
I was called out to a customer to help diagnose a problem with on of their machines. It has a Moeller PS416 CPu200 plc. The following LED's are flashing on the CPU:, RUN, READY, NOT READY,ERROR. The CHANGE LED is off. The battery was changed about a year ago, so that should be ok. The machine is in fairly regular use. No one has been inside the panel until me today. We didn't build the machine so I don't have the original code. the error LEDS suggest a problem with the Operating system. Can anyone shed any light on it?

Thanks in advance.

Been a while since I did anything with Moeller but I always found this company useful, http://www.applied-automation.com/about.shtml
Also there is a manual available for download that may help you,

ftp://ftp.moeller.net/AUTOMATION/DOWNLOAD/MANUALS/ENGLISH/HARDWARE/PS4_Series/PS416/index.html