Bypassing Spindle Alarms During Repairs for Fanuc CNC
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Something Fanuc CNC related that I just learned last week:
Many times during a spindle replacement service, it is necessary to disconnect or remove the spindle sensor (position coder or high resolution magnetic pulse coder.) The alarms that occur as a result of this disconnection may inhibit NC operations or other machine functions that would be desired to complete the needed repairs. Maintenance related M-codes may no longer work. This can be aggravating and add time to the job. For example, you may want to use service M-codes to change pallets (on a horizontal), and, due to the alarms, you might have to over-ride solenoid valves to accomplish the APC functions. I don’t know why I didn’t learn this years ago, but most sensor related alarms can be temporarily disregarded by the Fanuc CNC, so that the service work can continue without delays, by changing a parameter setting on the Fanuc control.
The alarms I’m discussing here are as follows:
AL-26
AL-27
AL-28
AL-41
AL42
AL-47
If you’ve worked on machines for a while, you’ve seen these alarms before.
Let’s first discuss AL-26, AL-27, AL-28. The Fanuc parameter manual describes the related parameter as follows:
“PLCS: Determines high-resoltion magnetic pulse coder and position coder signal disconnection detection.
0: Performs disconnection detection.
1: Does not perform disconnection detection.”
So, this parameter set to 1 = no alarm AL-26, AL-27, AL-28.AL
PLCS for a:
Fanuc 16=4007.5
Fanuc 15=3007.5
Fanuc 15i= (bit not specified)
Fanuc 0C=6507 (bit not specified)
Next let’s look at AL-41, AL-42, AL-47. The Fanuc parameter manual describes the related parameter as follows:
PCALCH: Enables or disables detection of alarms (AL-41,42,27) related to the position coder signal (9A11.C, 9A21.A, 9A50.A).
0: Detectes alarms related to the position coder
1: Does not detect alarms related to the position coder signal. When the spindle is not connected with the position coder on a one-for-one basis, set this parameter to 1 to avoid erroneous detections.”
Set this parameter to 1 = no AL-41, AL-42, AL47.
PCALCH for a:
Fanuc 16=4007.6
Fanuc 15=3007 (bit not specified)
Fanuc 15i=3007 (bit not specified)
Fanuc 0C=6507 (bit not specified)
When I get the opportunity to try this on various controls, I will update the “bit not specified” parameters mentioned above. Sorry about that.
As always, you can contact me at info@pinpointcnc.com. If I can help you out, I will.
Check out www.pinpointcnc.com for machine repair information, procedures and other products
Go to www.cncalarm.com for machine alarms and details
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Tagged With al-26, al-27, al-28, al-41, al-42, al-47, fanuc, spindle alarm