PMC System Alarm

What does 950 mean?

This alarm indicates a general system error within the Programmable Machine Controller (PMC) of the Fanuc Series 20 CNC. The PMC handles the machine's ladder logic, I/O, and interlock functions, so an error here means basic machine operations, axis movement, or tool changes may be impossible.

• Error in the PMC ladder program (e.g., syntax error, invalid logic).
• Faulty PMC hardware or memory module.
• Loss of PMC parameters or user data due to battery failure.
• I/O module malfunction or communication error with I/O devices.
• Excessive noise on the I/O lines affecting PMC operation.

Click steps to track your progress.

1. 1

   Check the PMC diagnostic screen for any specific sub-alarms or error messages related to the PMC.

2. 2

   Verify the PMC ladder program for recent changes or known issues. If a backup is available, try reloading a known good program.

3. 3

   Check the PMC battery (if separate from main CNC battery) and replace if low to prevent parameter loss.

4. 4

   Inspect all I/O modules and their wiring for loose connections, damage, or short circuits.

5. 5

   Power cycle the CNC system and PMC to clear any transient errors. If the alarm persists, the PMC module may be faulty.