Hello,

I'm the backup repair guy at the shop and one of our CNC operators is having an issue with an older machine. It's a Nakamura-Tome, I believe a model S-JR with a Fanuc OM control setup. The machine recently had it's batteries on the axis controllers replaced, and now it's throwing up 310 and 320 alarm codes for zeroing. That would be fine, except there is also a NOT READY ALARM preventing the operator from re-zeroing the machine. I dug through several forum posts on Google and tried what I could find. I made sure the limit switches were functioning, and that the weren't being contacted by the axis (ladder logic shows them working). I then checked the E-Stop switch and relay, both working fine. Finally, I checked the ladder logic going to G121.4, and now I'm confused. G121.4 should be a "1" for normal operation, and "0" when an E-Stop situation arises. However, there are two registers between the limit switch contacts and G121.4 that are open circuit, and I have no clue what they do or if they can be changed. I traced them through the ladder logic screens only to find them both going (in parallel with several other registers) to Y080.7, which was pulsing for some odd reason.

This is the extent of my knowledge on the machine, and I'm not sure where to look next. Any help would be greatly appreciated.