Need Help!- Fanuc21i-T - Reference point problem

[Dare]

Have CNC lathe, made by 'Metosa-Pinacho', model 'Mustang 200' control unit 'GE Fanuc 21i-T'.
The problem appears during searching reference points. When I turn power on, go in MDI mode, I find no possibility of manual moving (except in JOG mode). While inserting G28 and start cycle, nothing happends.
As far I know, engine has absoluthe encoders, and on the screen I see machine coordinates which is diferent from absoluthe coordinates.
Am I making some mistakes while finding reference points ?

Please give me some info if you have

Thanks

[dcoupar]

Did you try G28 U0 W0?

[Stebedeff]

I have a 21i-T as wel. I need to got to JOG mode and press the HOME button first for x axis. This is only for start up. The Z axis has a battery that memorises the home position. So no need to reference. But you do need to change battery after a while. I know that's not your problem right now. When changing this battery located on the fanuc axis board behind a black cover DO LEAVE THE MACHINE ON!!! or you lose you reference point.

[Dare]

I tried G28 U0 W0 but doesn't work.
I found in parameters 1815 that is APC set to 0 (incremental encoder) and I change APC to 1. After repower I have error message "306 APC ALARM:x-z AXIS BATTERY ZERO" I check battery (6V, 5Ah) and voltage is 0,132V (battery dead). I think that I lose reference point every time when I turn of machine. Am I right? Now I must find new battery but how can I set a new reference point?
Is "return to zero" changing absolute coordinates=machine coordinates?

Thanks

[stevo1]

As most machines are set up that you have to do a Zero Return at power up or the machine will not move as you are stating is your problem.

You have to move the machine in JOG off of the zero return limit switches about 1" or so. This is usually in the negative direction. Becarful as this is not the case with all machines. You then have to put your machine in "zero return" mode or "home" mode. then press and hold the axis to the positive direction. The machine will travel until it hits the decel dog and then travel at the "FL" feedrate set in your parameters until it sees the pulse marker. It will then call that home.

After this is complete for all axis your machine should work as normal.

Stevo

[hrh]

Just remember that there are machines which do not have deceleration switches for zero return.
With no dec switches you must move the axis manually by jog or mpg to a point which is determined by the machine builder. Usually the Z-axis will use the face of the chuck and then be moved a predetermned distance. The X-axis must be clocked to the chuck center for X0.000 and then moved a predetermined position.
Once the predetermined positions are reached, you must set parameter 1815 APZ to "1".
You will then be required to turn the power off and on.
Alternatively you can move the axes to positions you can observe on the slide covers (oil marks or wiper marks) of the old zero positions and then set the parameter 1815. Note that this is a very rough approach but less time consuming.

[Dare]

Thanks people...
After a new battery installation, and setting reference point (as described) everything is OK. This machine has not a decelaration dogs and limit switches but coordinates of the ref point is stored in memory. I set a new value for +/- limit, new absolute coordinates for reference point and that's it...
Special thank's to Al_The_Man for user and parameter manual.