Recovering from Memory Parity Error on Fanuc 21M

I have an older Fanuc 21M based CNC milling center. I have been getting it up and running for the first time. During this process I managed to get a memory parity error on boot. I had to use the 8+9 held on power to reset the parameters to boot up. Now that I have, if I go offset settings, I can't change the channel or punch settings (even though the parameter write is on). But I can edit them from the parameters menu.
Now, i tried to use the parameters screen to 'punch' out the parameters over serial, but the soft key doesn't move to the second list of options that has the PUNCH and READ options anymore.
I manually updated parameters 001 through 0140, but still nothing seems to be working. Does anyone know how to get the fanuc controls back up and running from this point?

What alarm code did you get? The normal procedure to clear a parity error is not holding the 8 and 9 keys. Where did you get the information to try that?

You will probably have to initialize the control and reload the parameters from your backup.

Vancbiker said:

What alarm code did you get? The normal procedure to clear a parity error is not holding the 8 and 9 keys. Where did you get the information to try that?

You will probably have to initialize the control and reload the parameters from your backup.

Click to expand...

Sounds like he tried to punch the parameters out AFTER the 8+9 key trick... So hopefully he had a backup FIRST?

I have my parameters yes, but wondering why the punch and read menu items are no longer available where they normally were.

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TeachMePlease said:

Sounds like he tried to punch the parameters out AFTER the 8+9 key trick... So hopefully he had a backup FIRST?

Click to expand...

What is the 8+9 trick? what is it supposed to do?

Casmer said:

I have my parameters yes, but wondering why the punch and read menu items are no longer available where they normally were.

Click to expand...

Most likely because you have cleared the option and configuration parameters. When that happens the control is in it's lowest possible configuration. I'd have to look at some lists, but IIRC that means no
RS232 reader/puncher interface.

Are you going to post what the parity alarm number was and where you got the info to press 8 and 9 at power up? The 8,9 is not the usual method to clear memory to get rid of a parity alarm. If you'll post some more of the back story it may help us understand what all went wrong and then figure a path for you to recover the control.

Casmer said:

I have my parameters yes, but wondering why the punch and read menu items are no longer available where they normally were.

Sent from my Pixel 3 XL using Tapatalk

Click to expand...

Hello Casmer,
As Kevin, AKA Vancbiker, states.

Reset and Delete Keys pressed and held whilst the control is powering up is the usual way to initialize memory, but you better make sure you have a backup of parameters, including options, before carrying out that action. However, it would seem that you have already wiped the parameters.

After initializing the memory by the aforementioned method, you have a once off opportunity to reload parameters via an RS232 link. If you recycle the power to the control after the Reset/Delete process and before reloading the parameters, that opportunity is gone and you need to repeat the Reset/Delete process to get to that point again.

Immediately after the Reset/Delete process has been executed, the Fanuc default RS232 settings of 7 Data Bits, 2 Stop and 4800 Baud Rate exist. Accordingly, by setting the RS232 protocol on whatever external device software you're using to:

Xon/Xoff Handshaking
7 Data Bits
2 Stop Bits
Even Parity
4800 Baud Rate

you should be able to download the parameters to the control. You need to press the EOB button on the control when you initiate the transfer to the control so that the Option Parameters are loaded.

Regards,

Bill

Thank you, I had read on a forum post somewhere that if the Parity error 112 that I received on the fanuc is displayed you have to initialize the memory and reload the parameters. I didn't find any other way to get out of that and made the mistake. I will try that reload steps you provided.
If I do get another parity error how do you fix the issue if the control system will not boot to the main menu?

Casmer said:

...... the Parity error 112 that I received on the fanuc is displayed ......

Click to expand...

If you mean alarm 112 that is a divide by 0 alarm. This is not a parity alarm. It occurs due to an error in a macro program. Parity alarms are in the 9xx range. Alarm 912 is an SRAM parity alarm. Is 912 the alarm code you had and not 112?

Alarm 912 is a common alarm that occurs when the backup batteries have failed or been disconnected. Another common cause is turning on an option parameter for a larger memory size than the installed hardware configuration supports.

I should have taken a picture. But at this point I am back up and running, I set the 9000 to 9999 parameter values manually, cycled the power and then it was back up and running again. I didn't know I had to set those parameters first. A tech rep at Methods helped me out over the phone.