Danfoss micro VLT FC51 problem: goes from Auto to OFF

[Phanx11]

Hello everyone

I have a problem with several single phase Danfoss micro VLT FC 51 drives. All are ran by a PLC through digital contact, reference is supplied by analog input and all parameters are read over Modbus RTU.

The problem is i sometimes see the drive wen't from Auto to Off and just sitting. They do sometimes, like once a day get an alarm, number 8 (Undervoltage DC bus) and in the drive setting i have set to infinitely recover. But it should still stay in Auto mode, not revert to OFF.

I've looked many times in all the manuals online that i could find and couldn't find the answer. At the same time, perhaps someone knows if any of the drive's digital inputs can be tied to remotely activate AUTO mode or if it can be done via modbus? It's incredibly annoying to press AUTO each time on the LPC...