Stuck In Mm On Fanuc 18t, Help!

[TEVAN]

I'm a new member, and I need a little help please.
On the offset page shown below, my input unit
for INCH got turned off on a Fanuc 18T lathe.
I think there's a bit turn off somewhere in the parameters,
that does not allow me to turn INCH back on.

This page looks something like this:

SETTING (HANDY)
PARAMETER WRITE = 0 (0: DISABLE 1: ENABLE)
TV CHECK = 0 (0: OFF 1: ON)
PUNCH CODE = 1 (0: (0:EIO 1:ISO)
INPUT UNIT = 0 (0: MM 1:INCH)
------ ^
------ THIS LAST ONE ABOVE IS
------ NOT TURNING BACK ON.

So my question is, does any one know whats preventing me
from just typing in #(1) and reactavating INCH?

[Al_The_Man]

Are you in MDI when changing the bit, I thought you could change it without the PWE bit being set, but you may have to, PWE should be on the Handy screen at the top, also check P0 bit #2 for a 1 (Inch mode).
You may have to power down and up again to store it in memory.
You may be able to change it with G code G20.
Al.

[Dan Fritz]

You should be able to key that bit in in MDI mode. Just move the cursur to it and enter "1" then press INPUT. The control must be in MDI mode, and the memory protect key switch must also be off.

This bit should also change with the status of G20/21, so key in a short program with a "G20" command, run the program, and see if the bit has changed to "1" for INCH

[TEVAN]

Thanks guys for the reply's.
I did have MDI on, I forgot to say that.
I tried G20/G21, it alarmed (illegal G code) while in MM??????
So I found the backup parameters on floppy, and loaded them
in my computer, opened with microsoft works, printed just the
9000 parameters.
I compared the originals with what was in the machine, and near the
top was (original 9920-00010000).
The (machine 9920-00000000) was missing the above bit.
When I turned it on, it allowed me to turn
---------INPUT UNIT = 1 (0: MM 1:INCH) back on to INCH.
Thanks again for your reply's

[Dan Fritz]

I guess you've just discovered that inch-metric is an option on the Fanuc control. If you turn the option off, the control only has the ability to run in the same increment system as the ballscrews (in this case, metric). Running a machine with metric ballscrews in inch or inch ballscrews in metric requires the option. Since virtually every control out there has this option, no one thought to suggest this as the problem. Nice goin'

[TEVAN]

Originally Posted by TEVAN Thanks guys for the reply's. I did have MDI on, I forgot to say that. I tried G20/G21, it alarmed (illegal G code) while in MM?????? So I found the backup parameters on floppy, and loaded them in my computer, opened with microsoft works, printed just the 9000 parameters. I compared the originals with what was in the machine, and near the top was (original 9920-00010000). The (machine 9920-00000000) was missing the above bit. When I turned it on, it allowed me to turn ---------INPUT UNIT = 1 (0: MM 1:INCH) back on to INCH. Thanks again for your reply's

9920-(00100000). THIS IS THE CORRECT BIT, JUST INCASE SOMEONE ELSE
NEEDS THIS PARAMETER TURNED ON. I WAS ONE BIT OFF ON MY LAST POST.