FanucOM machine coordinates

[bcdnm]

Howdy,

The machine has three coordinates on the position screeen.
Machine, ablsolute, and relative.
Absolute resets when the machine is turned off.
It seems that the X0,Y0,Z0 point on the machine coordinates is beyond the limit switches on the machine at least on 2 axes.
Is this normal?
Can it be reset?

thanks,

Hawke

[Dan Fritz]

The "machine" zero point should be the zero-return point, or the point that you reference zero the machine to after power-up. The machine coordinate system is in metric if your machine has metric ballscrews, and in inch if it has inch ballscrews.

The "Absolute" position display is set with your coordinate system, or with the G92 command to preset absolute zero. This point can be anywhere, and it's the point that you program to.

The "relative" coordinates can be set anywhere you like. These are frequently used to reference some convenient point on a fixture, etc. They have nothing to do with your programing coordinates really. You should be able to use the ORIGIN button to reset the absolute or the relative display, but the machine display is zeroed out when you zero-return, and that display will not change.

[ktb100]

I agree with Dan Fritz 100%. The only thing I would add is that the relative position is used mainly as you would use a digital read out on a manual mill. It has no bearing (as stated) toward programming.

[la_coterie]

It seems that the X0,Y0,Z0 point on the machine coordinates is beyond the limit switches on the machine at least on 2 axes. Is this normal? Can it be reset?

or do you mean the home switches?

I seem to remember actual X0 Y0 Z0 position from home switches can be set in parameters so as I understand it when referencing the machine at startup the coordinates read other than 0.

If that's what you mean, next time I have insomnia I'll look in the book

[Dan Fritz]

You can set the Fanuc 0M to preset the "absolute" position registers when you manually zero-return. The values are set in parameters 708 (for X) 709 (for Y) and 710 for (Z). If you zero out those parameters, then the absolute registers should preset to zero when you zero-return.

There is also a parameter 010, bit #7 (the bit on the far left) that determines whether or not the automatic coordinate setting is done or not done when you zero-return. If that bit is a "1", then the values of parameters 708-710 preset the registers, and if that bit is a zero, the registers are not preset.

My guess is that you have a value set in parameters 708-710 which places absolute zero outside of the limit switches, and your parameter 010 bit 7 is a "1".

[la_coterie]

Ah yes!

those were the ones I was thinking about
well done!