Hello Setha;

You suspect the PLC's power connection for your loss of hardware configuration, this is a possiblity.

Do you think the power supply module is the source of your problem, in which case your first step should be to put in a new unit, or is it the plant power that dipped, caused a brownout and left the CPU without power for a very short period?

If that is the case, a 24VDC UPS module would allow the PLC to survive these conditions. Here is a link to Siemens Sitop UPS modules, you could also look at other manufacturers with similar offerings.

https://new.siemens.com/global/en/products/automation/power-supply/dc-ups.html

Hope this helps, 

Daniel Chartier