Feedrate Override Pot not working on Fanuc O-M

[jamesgates1000]

Hi, The feedrate Override pot on my denford Triac (Fanuc O-M) doesnt seem to work. I have put an m49 in the beginning of my program to ensure that any M48 is cancelled but still does full feed regardless. Anyone know how I can check if the Pot is working?

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[Superman]

You have them the wrong way round

M48 allows override to work
M49 locks overrides at 100% ( this is used on a lathe during the threading cycles )

Also, look at this thread... LINK

[jamesgates1000]

Didn't have email notifications turned on so only just seen this, thanks for the replies. I tried putting an m48 in the program and setting parameter #3004 to 0 just in case it had been switched off. I aIso had a look inside and it is a multiplex type pot, I measured some changes in resistance across the connections and can see some bits changing in the diagnostics. I will make a note of what numbers when I am on my machine next although I remember that g121 only bits 0 and 1 were changing and g126 bit 4 was set at 0. Any idea what I could do next to trouble shoot this or does it sound like I need a replacement.

[cjfisher]

James,

It may not be a pot, but a multi-position switch. Do you have schematics for your machine? If you do you'll be able to find the override switch (more likely)\pot in the diagram and that should give you information on where it is hooked into the logic ladder.

cjfisher

[jamesgates1000]

]#

Yep its a multi position switch, checked continuity on each of the wafers and the switch is good, any idea where i go from here?

[cjfisher]

James,

What flavor is your control? If it is a model C or D you have the ability to look at the ladder logic. At this point I would be looking through the logic while changing the position of the switch until I found the rung that the override switch was tied into (if your lucky the machine builder will have indicated where the various signals tie into the controller). You many find that there is additional logic that "blocks" the override until it is satisfied. You may also have an override disable switch on the front panel.

cjfisher

[jamesgates1000]

Hi, thanks for the help. I have solved the issue. I found the rungs that the switch was tied into on the ladder, X021.0, X021.2 X021.3 X021.4, only one of these was changing when i replaced the switch and only one diagnostic bit was also changing. I wiggled a Honda 50 pin connector and two bits changed. Opened it up and three wires had broken off. I managed to work out which one went to which pin by matching up the broken solder. re soldered now working as it should do.

[sorenbj]

hope it´s ok to ask in this thread

i cant get feed hold and feed override to work on my fanuc OMD from 1998,
if i go to parameter 6200 and change that and start the machine op again it all works, until the next time my machine i turned on,
i will try m48, and see if that helps,

best regards