Ok, admittedly I am new to this, but I am working on a ~1998 vintage SR-32 with a Fanuc 16T control (so says the frame around the CRT monitor).
The problem is that the operator selected the zero return button then pressed the axis directional button and nothing happened. After messing around with it a little I have determined it doesn't seem to even be going into zero return mode at all. The bottom left of the CRT which indicates which mode the machine is in indicates MEM (instead of REF I presume) when you select the zero return button. The same is true for the Macro button.
From left to right:
(Button name - mode displayed on monitor)
Edit - EDIT
Memory - MEM
MDI - MDI
Macro - MEM
Jog - JOG
Step - INC
Zero Return - MEM
I can't say if this is normal (I think not), but if you are already in zero return or macro mode (the LED's light up on the buttons), and you press the button a second time, it flashes RESET at the bottom of the screen the same way it does when you press the reset hard key. It's almost like its half way in the right mode, then when you hit it again it thinks you're hitting the reset button? It does not flash reset if you are in edit, MDI, jog, or step mode and hit any of those mode buttons a second time.
Obviously it seems as if the control isn't "seeing" something to make it transition to zero return mode. When looking at the diagnostic screen, the X address for the mode buttons all work and change the bits accordingly. When looking at the ladder diagram with my untrained eye, it looks like its true from left to right after you select zero return then press an axis directional button, yet nothing moves. In JOG mode, all the axis move correctly.
I'm kind of at a loss, and it seems Star thinks its a bad keyboard. I physically tested the buttons with a multimeter and found no problems. I also don't think this is the issue because the PMC (correct term?) is seeing the correct signals from the buttons when pressed while watching the bits change. Everyone I have talked to there is simply frustrating me telling me that what is happening isn't possible.
Fanuc was slightly more helpful, but kept saying that typically the G43.7 should change to a 1 when zero return is selected - mine does not. However, when searching the ladder for a G43.7, it also says "Address is nothing" implying it's not there. You can search and find G43.1 or G43.2 just fine however, which are associated somehow with the other mode buttons. Fanuc seems to think Star might have used a different address or whatever for zero return, and said that until he knew what that was he couldn't help much more.
If anyone has any ideas, or needs more information, I would love to help you help me!