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.
What you need to look for is the coils for those 2 address'.
Enter R602.1 and use the W-SRCH button. This will take you directly to the coil. Figure out what is turning it on.
Then repeat for R603.2.
If R602.1 does not return a coil from the search try R602 and SRCH. Its possibly there is a register used.
This looks like an older control so hopefully there is no Macro executer to worry about.
I traced both registers back to F149.7, which a quick Google search tells me is the "CNC Ready" signal. However, that only makes me more confused. What triggers the ready signal? Apparently if its open, G121.4 goes to "0", which makes some sense, but I still don't know where F149.7 originates. Is it part of a parameter?
Edit: Some additional info from the operator. The machine was previously working, then a "Watchdog Timer" error popped up. The machine had it's parameters wiped to eliminate the error, and now we're stuck here.
MA is basically control ready. They are using it as a latch circuit forcing a power down to reset the coil.
When the memory was reloaded were the PMC parameters also set. Its possible there aren't any but most OEM's use at least a few timers or the old equivalent of Keep relays.
So now searching for the coils R571.4 and R571.5 would guide you further into where the problem lies. - Provided PMC parameters aren't missing and all NC parameters are correct.
Now all of this may be for naught depending on what the watch dog alarm was as it may just happen again if whatever caused it is not resolved.
Nakamuras used to have a button on the side of the control you held like a release button and then with power on also some of the machines when homed you had to index the turret as it had a homing cycle aswell -------------We had TW30 and TW10/20 many yrs ago and about 20 of them at the time
If this is not on this machine hold P and Cancel and then power up while holding -----This then allows the machine to look for limit switchs if fitted
Fanuc OM "NOT READY ALARM" troubleshooting
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