Absolute Pulse Coder is Faulty

What does 304 mean?

These alarms indicate a malfunction or failure in the absolute pulse coder (encoder) system for one or more axes. This prevents the CNC (Fanuc Series 20) from maintaining or establishing the absolute position of the axis, leading to potential loss of position data.

• Damaged or faulty absolute pulse coder.
• Loose or damaged cable connecting the pulse coder to the servo amplifier or CNC.
• Electrical noise interference on the pulse coder signal lines.
• Malfunction of the servo amplifier's encoder interface circuit.
• Contamination or physical damage to the pulse coder itself.

Click steps to track your progress.

1. 1

   Inspect the absolute pulse coder and its associated cabling for any visible damage, loose connections, or contamination.

2. 2

   Verify the continuity and insulation of the pulse coder cable from the encoder to the servo amplifier using a multimeter.

3. 3

   Check for strong sources of electromagnetic interference (EMI) near the pulse coder or its cable. Ensure proper shielding and grounding.

4. 4

   Examine the diagnostic screen for specific pulse coder errors that might indicate the nature of the fault (e.g., battery error, communication error).

5. 5

   If possible, swap the pulse coder with a known good one from another axis or replace the suspected faulty pulse coder.