1756-L61 program vanishes

[credard 0]

This is a new one for me. Large installed system, working fine for almost a year. 3 1756-L61's connected via ControlNet. Panels are hundreds of feet apart. All use serial port for barcode scanner. Ethernet used for programming and comms with legacy PLC5 system. Customer reported that one processor lost the program, suspect nearby welding as cuprit. Downloaded program, ran for a week, ,program erased again. Problem became more frequent until it would not last more than an hour. Replaced processor, problem seemed resolved. Now, it is beginning to happen to a different processor. Plant engineer states that the system stops running and Enet comms with HMI is lost, RUN indicator is lit, no BATT or FAULT LED. Interestingly, he can communicate through serial, (which should be in User mode for scanner). Can't communicate via ethernet. If he tries to upload, no program found. Any ideas?

[OZEE 5]

Which firmware version? It seems like there was an anomoly in one version that did this. Perhaps one of the 12's or 13's??? (Might be wrong... I'm out on the road, so I don't have access to all of those notes...)

[credard 0]

ver. 15.4

[TConnolly 13]

See the remainder of the tech note for resolution.

[credard 0]

Perfect! Thanks so much!

[Contr_Conn 4]

This technote has nothing to do with L6x controllers, it is only for L55 What you need to do is contact techsupport: They will give you instructions on how to extract debug information out of PLC and send it for review.

[finfin 0]

Please keep us posted on this. AB has a tendency not to bother.