| Symptom | Likely 900 Parameter Issue | Fix | |---------|----------------------------|-----| | | 903 bits 7-6 wrong (servo type mismatch) | Change analog/digital to match actual drives (e.g., α series = digital). | | Turret won’t index; no PMC signals | 908 bits 7-4 incorrect | Check if turret is hydraulic (bit7=0) or servo (bit7=1). | | M19 orientation spins but doesn’t stop | 901 bit7=0 (orientation disabled) | Set to 1. Also check 912 bits for encoder feedback. | | Alarm PMC SYSTEM ALARM 20 | 902 bits 3-0 wrong (diagnostic memory size) | Increase memory size (e.g., from 4K to 8K). | | Cannot edit ladder | 904 bit7=0 | Set to 1 ONLY for editing, then return to 0. | | No live tool indexing (C axis) | 900 bit5=0 (C axis missing) | Set binary to include C axis. Also enable param 912. |
Editing these parameters is a high-risk operation. Improper changes can lead to system instability or hardware crashes. fanuc ot 900 parameter list
| Bit | Function | |------|-----------| | 7 | 0 = PMC ladder edit disabled, 1 = enabled (use with extreme caution) | | 6 | Parameter write via MDI disable | | 5 | Backup ROM writing enable | | 4 | CNC data save to memory card | | 3 | Boot system modification lock | | 2-0 | Reserved (usually 000) | | Symptom | Likely 900 Parameter Issue |