Don't want to have to "HOME" the Fanuc OT

[desw]

Hi All,
Fanuc OT-A control. On power up automatic operation is impossible without homing both the X and Z axis. I want to disable this so it becomes optional / unnecessary. Could anyone please help me with the parameter I need to change for this. Thankyou in advance. desw

[stevo1]

I have never set up my machines this way before so I would not know what parameters that you need to set. However I am not 100% but I thought that the only way that you can do this is if the Axis are driven from the PMC. I don't know if this requires certian ladder logic in order to achieve this. Like I said I am not 100% but I think this requires more then just changing of a parameter.

Is there a reason that you are trying to do this? I would think if the machine is already set up for have to reference the machine it would be easier to just reference the machine then having to change over to no reference.

Do you have the parameter book for this control? If not send me a PM with your email.

Stevo

[Al_The_Man]

The ladder might be programmed so that the homed bit has to be on to allow cycle start.
There are bits in 0074 #0~#3 when set to 1 for each axis that allow a commanded move to occur without an error warning, except G28, when no return has occurred.
Al.

[ben_heinman]

MTB uses keep relays to enable/disable the option to home the machine.

[Dan Fritz]

There is a parameter to determine if rapid traverse is limited to a lower setting before zero-return, but any interlock to prevent auto operation before zero-return would be in the ladder logic. Maybe the MTB assigned a PC parameter for this, but frankly, I doubt it.

[Jung]

Originally Posted by desw Hi All, Fanuc OT-A control. On power up automatic operation is impossible without homing both the X and Z axis. I want to disable this so it becomes optional / unnecessary. Could anyone please help me with the parameter I need to change for this. Thankyou in advance. desw

If you could send me PMC ROMs, I can help you to see if ladder have this option.

[EECENOD]

UNLESS YOU SPECIFIED ABSOLUTE ENCODERS (YOU WILL RECOGNIZE THEM BECAUSE THEY HAVE BATTERY BACK-UP) PARAMETERS 21 AND 22 REFLECT
THE BITS NECESSARY TO BE SET FOR EACH AXES. NORMALLY AN OTA DOES NOT INCORPORATE ABSOLUTE ENCODERS. WITH ABSOLUTE ENCODERS EACH TIME YOU POWER THE CONTROL OFF AND RETURN POWER TO THE CONTROL THE POSITION SCREEN WILL COUNT UP TO THE POSITION IT WAS IN WHEN POWER WAS REMOVED

[cncserveng]

Its not that simple, you need hardware and software for abs encoder systems.

The only way I know of is to turn off the ref function thro' parameters and revert to a more basic system when you will need to actuate the reference bits manually to arrows marked on each axis after an axis alarm.

Why dont you want to ref the machine on power up? it was always the way untill a few years ago.

[stevo1]

Originally Posted by cncserveng it was always the way untill a few years ago.

Which is about when he posted the original question

I agree though I don't know what the issue is with having to reference the machine at powerup.

Stevo

[cncserveng]

Yes and the question was how to turn it off, but the questioner needs to understand the reason for referencing a machine. It is all about "known positions", for example the XY position of the table and the Z position of the table top relative to the spindle centre line and its face.

Without these, tool changing etc; cannot be achieved because the machine doesn't know where to go. If you try and run a program without referencing there usually comes a "need reference return error".

Abs encoder systems are still referenced, but they store the positions at power off. The questioner needs to understand the accuracy of the machine will be removed if no reference positions are active. Older machines sometimes had incremental systems, but rarely had toolchangers etc;

[HuFlungDung]

I could imagine the odd part setup that was so cumbersome to make, that you could not permit the machine to move into certain positions (like the all axis home position after a power outage) because of collision. One could still offset the machine coordinate system from the power up zero display with a G92 (if you knew for sure where a certain position was). But the PLC would have to permit it.

[stevo1]

cncserveng...I was just being sarcastic considering the OP was over 2yrs ago and he never responded back to any of other posts. I have done plenty of installs and retros so I know why the machine needs to be referenced. I just don't understand why he has an issue with not wanting to do it.

Hu...that is a good point. I never thought about that. I have not come across a machine that would let you run without referencing it.

Stevo