Fanuc spindle alarm d2 means communication between a SERIAL sensor and the Spindle Amplifier is disconnected. Newer spindle configurations use serial-interface sensors (digital data link instead of analog A/B signals); d2 is their equivalent of the classic ‘sensor disconnected’ alarms (AL-73/84). Fanuc's triage: at start-up, all causes (a)–(d) apply; on a machine that has been operating normally, only (c) and (d).
Commissioning / first-start causes
- (a) Parameter setting error: the sensor-setting parameters must declare the serial sensor correctly — check per the START-UP section of B-65280EN. Wrong sensor type declared = the amplifier listens on the wrong protocol.
- (b) The amplifier does not support this sensor: serial sensors require compatible amplifier hardware/software — verify against the ‘Parameters Related to Detectors’ section of B-65282EN. An older or wrongly-chosen replacement amplifier simply cannot talk to the sensor — the fix is the right amplifier, not persistence.
Any-time causes
- (c) Cable broken or connected incorrectly: the leading physical cause — reseat both ends, inspect pins, walk the run, wiggle-test, and replace with the correct spec cable if in doubt. Serial links fail harder than analog ones: marginal analog degrades, marginal digital drops.
- (d) The amplifier is defective: the serial receiver stage on the control PCB — board-level repair or exchange, once the cable is proven.
Tip: d2 belongs to a family — d3 (data destroyed by noise), d4 (position jump), d9 (sensor internal error), E0/E1 (pulse/Z checks). Which one you get localizes the fault: d2 = link dead (cable/support); d3 = link noisy (shielding); d9 = sensor itself. Read the code precisely before reaching for parts.
Related guides
- Fanuc spindle alarm d3 (serial data destroyed by noise)
- Fanuc spindle alarm d9 (sensor inner circuit)
- Fanuc spindle alarm 73 (analog sensor equivalent)
d2 on a serial-sensor spindle? JJ Automation verifies sensor/amplifier compatibility, stocks serial sensor cables, and repairs amplifier receiver stages at component level. On-site diagnosis in NCR. WhatsApp us or call +91 88022 12394.