That's a bummer and it's pretty strange how a PLC would suddenly lose its memory?
From the picture I can see that is a Mitsubishi PLC , they are fairly reliable, and I have never heard of a PLC to suddenly have a memory wipe.
It's a real shame your elevator company didn't download the logic from the PLC and save it to a PC, then it would be a straight swap over. Those PLC arent too difficult to source...
If the battery goes it will looses memory. Also if the company pulled the PLC and the battery was weak when they went to download it then the owner would blame the compnay. If they are so reliable then why woluld they even pull it to download? Just seeing it both ways. I dont know about the Mistudishi drives but the Omrons need tools and computer sofware to download.
