1771-DB, PLC2 ASCII BASIC Module - Faulting Processer

I've got a customer who has a PLC2 system which uses an ASCII-BASIC module to communicate with another system. A few days ago, comms. stopped and everything seems to be pointing to the ASCII-BASIC module. They have plenty of spares, but the tech onsite replaced the A-B module, along with the original EEPROM, but when he re-started the system, the PLC2 faulted. I don't know what kind of fault they experienced.

Has anyone had this type of problem with a similar PLC2 application? I'm thinking that the firmware in the EEPROM is probably not compatible to the PLC2 version - or something of that sort.

Not an expert, but

I think it unlikely that any module firmware is directly causing the processor to fault since the module communicates with the processor via block transfers only.

I suppose it's possible that the EPROM could be corrupted and is causing the BASIC program to send something which faults the PLC-2 - in which case the validation logic, assuming any exists, might need looked at also.

It'd be tedious but if an ASCII terminal can be rigged and the BASIC program code is available and isn't too long, the program could be typed in by hand and tried that way.

Thanks. I had anticipated having to manually enter in the ASCII-BASIC program if it turns out that the EEPROM is corrupted. I downloaded the 1771-DB manual for some good night reading (yawn), but it actually does contain some good information.

I'll know more when I'm onsite next week and actually looking at it.