Danfoss AK-PC 740 pack controller

I have 4 x 740 pack controllers 1 is ok but other 3, the comms module is burnt out almost as though 240v has been put on the comms module.
Has anyone come across this before, the pack controller which is ok is the 2nd controller in the network from the 255.
Bit of a strange one never come across this before.
The pack controllers are working but not communicating with the 255, this is what danfoss have said they have found today onsite.
Thanks in advance for any replies:-]