Problem- M25 on Fanuc OM Control

[CHampshire]

Hello everyone. I have an issue on my Bridgeport Mill. In order to pop the tool out of the spindle, you must send the machine to the home position. I accomplish this via M25. Normally this is ok, unless tool length has been called up. If tool length is active the machine tries to rapid down into the vice.

I have machine zero set on the vice ways so that all my tool lengths and w.s. are positive numbers. I assume that when the macro is called to return to my reference point it tries to return to my part zero. Here is the macro called up when I enter M25

O9002;
G91 G28 Z0.0.;
M25;
G90;
M30;
%

Seems like its a pretty simple macro and I tried entering a G49 in before the return to reference point line. Still it wants to rapid back to z zero.

Any ideas on how to keep this from happening. Thanks in advance.

[Al_The_Man]

AFIAK, G28 should send the axis to the Machine zero point.
This should ignore any part zero, as long as your machine zero is in the right place for tool change?
Al.

[CHampshire]

Glad to know that I'm not the only one puzzled by this. I was hoping that this wasn't a dumb question.

[angelw]

Originally Posted by CHampshire Hello everyone. I have an issue on my Bridgeport Mill. In order to pop the tool out of the spindle, you must send the machine to the home position. I accomplish this via M25. Normally this is ok, unless tool length has been called up. If tool length is active the machine tries to rapid down into the vice. I have machine zero set on the vice ways so that all my tool lengths and w.s. are positive numbers. I assume that when the macro is called to return to my reference point it tries to return to my part zero. Here is the macro called up when I enter M25 O9002; G91 G28 Z0.0.; M25; G90; M30; % Seems like its a pretty simple macro and I tried entering a G49 in before the return to reference point line. Still it wants to rapid back to z zero. Any ideas on how to keep this from happening. Thanks in advance.

If O9002 is your Macro program, and its called using M25, you're calling it again within the Macro, and the Macro program is being terminated with M30 rather than returning to the program from where the Macro program was originally called.

Unless there is another program that is called by M25, you will achieve the same result by just programming G91 G28 Z0.0 in your main program and not call the Macro program.

If you can find another program that is called by M25, post it so that every one can take a look. Look at parameter numbers 0240 to 0242, corresponding to program numbers O9001 to O9003 respectively, and see which one holds the setting "25"

Regards,

Bill

[underthetire]

I agree with the double m25. I've seen this morenthan once if the g91 is not called before the g28, but your macro has it in it. How about being safe and just cancel tool length offset in the beginning of the macro?

[CHampshire]

Originally Posted by underthetire I agree with the double m25. I've seen this morenthan once if the g91 is not called before the g28, but your macro has it in it. How about being safe and just cancel tool length offset in the beginning of the macro?

Thanks for the reply.

I tried editing it like this earlier today and it did the same thing. Here's what I did:

O9002;
G49; (tool length cancel)
G91 G28 Z0.0.;
M25;
G90;
M30;
%

I put it here so it would cancel tool length first before any Z moves.

Perhaps I am missing something with the G49?

Also I should be a little more specific. I only use the M25 In the MDI page. It's not posted out in any programs. Tool length is the only thing that I can come up with that screws with it.

[underthetire]

Think I see the problem, not positive though. All our return macros and programs must have a g0. Should be
G0g91g28z0. I'll bet you still have a g1 active.

[angelw]

Originally Posted by CHampshire Thanks for the reply. I tried editing it like this earlier today and it did the same thing. Here's what I did: O9002; G49; (tool length cancel) G91 G28 Z0.0.; M25; G90; M30; % I put it here so it would cancel tool length first before any Z moves. Perhaps I am missing something with the G49? Also I should be a little more specific. I only use the M25 In the MDI page. It's not posted out in any programs. Tool length is the only thing that I can come up with that screws with it.

So what does M25 do? From your OP it seemed like it was used to call a Macro program.

As Al stated, if the Z Zero Return position is correct for your tool change, all you need to do is program G91 G28 Z0.0; the tool offset and part Zero will be irrelevant. The Tool Offset for the next tool will be applied when you call it's offset.

Regards,

Bill

[angelw]

Originally Posted by underthetire Think I see the problem, not positive though. All our return macros and programs must have a g0. Should be G0g91g28z0. I'll bet you still have a g1 active.

G28 is a non modal, two shot command, Reference Return through an intermediate point, and requires no priming with G0. It moves at rapid traverse speed.

Regards,

Bill

[sinha_nsit]

Try to find out whether M25 calls a sub/macro, or it is MTB-defined code.

[CHampshire]

When I use M25 In MDI it calls up program 9002. That's why I posted that program. Here is 9001 which is what it uses to do an actual tool change.

%
:9001
N1G80G91G30Z0.0M65
N2IF[#1012EQ1]GOTO6
N3M66
N4G91G28Z0.0M67
N5G91G30Z0.0M68
N6G90M99
%

Bill, Parameter #241 has a value of 25 in it.

[angelw]

Originally Posted by CHampshire When I use M25 In MDI it calls up program 9002. That's why I posted that program. Here is 9001 which is what it uses to do an actual tool change. % :9001 N1G80G91G30Z0.0M65 N2IF[#1012EQ1]GOTO6 N3M66 N4G91G28Z0.0M67 N5G91G30Z0.0M68 N6G90M99 % Bill, Parameter #241 has a value of 25 in it.

The 25 set in #0241 means that O9002 is call by M25, accordingly you're correct with the first program you posted. However, when an M code that is defined in the parameters #0240 to #0242 is specified in a subprogram that is called by an M or T code, the defined M code is treated as an ordinary M code. Accordingly, M25 must have a function defined by the machine builder. Is there an M code list in any of your manuals that defines the function of M25? It would be helpful to know what M25 does when treated as an ordinary M code.

Is there a number in parameter #0240, perhaps the number 6?

There is nothing in either of the 2 programs that you've posted that would normally cause the Z axis to behave as you've described when a tool length offset is active. The only thing I'm not familiar with in O9002 is the function of M25.

The way you're using G49 is correct, and should cancel the active offset. H0 can also be used to cancel an offset.

Regards,

Bill