FANUC Alarm SRVO-070 — SERVO STBERR alarm
Error- Hardware
- Pulsecoder (encoder)
- Controllers
- R-J3iB / R-30iA / R-30iB
- FANUC class
- SERVO2
- Hardware family
- FANUC Pulsecoder, backup battery and position loss alarms
Manufacturer wording — SERVO STBERR alarm (Grp:%d Ax:%d)
The manual prints placeholders; your controller fills them in with the real group, axis or number.
FANUC SRVO-070 (“SERVO STBERR alarm”): A serial data start bit or stop bit error occurred. First check: 1. Check the shielding for the pulse coder cables to ground. Likely part: Pulsecoder (Pulsecoder (motor encoder)).
Updated 2026-10-22 · LogrobotLM reference
Description
A serial data start bit or stop bit error occurred.
Remedy
1. Check the shielding for the pulse coder cables to ground. The ground wire is the yellow and green wire connected to the robot base. 2. Inspect the pulse coder cable set for breaks, internal robot set, and P1 cable running from the robot to the controller. WARNING: By completing the next step you will be altering the positional reference for the robot since you are replacing hardware. You must slowly verify all positional data and touch-up any paths or points that have changed. Otherwise, you could injure personnel or damage equipment. 3. Replace the pulse coder and remaster the robot. 4. Replace the P1 cable. 5. Replace the internal cable set.
Field diagnosis
Error on the start or stop bits of the Pulsecoder serial frame.
What to check
- Check the encoder cable connection (robot connection cable for the robot axes) and the connection of the shield to the ground plate, then replace the Pulsecoder, the amplifier, the robot connection cable.
- Note: Handled together with 068/069: the three codes have the same list of suspects.
- Diagnostic sequence “Encoder link, not the encoder”: The three codes 068/069/070 appear together, sometimes with PHAL (064) or CSAL (066): the encoder serial link is at fault, and the encoder codes accompanying them are symptoms. Robot connection cable connectors at both ends, shield grounding, robot connection cable, robot internal cable; encoder and amplifier only after that. Do not replace the motor first.
Part to check / replace
FANUC SRVO-070 points to the hardware below — start here before ordering.
Tap a part for every code that points to it — and verify the exact variant for your controller before ordering.
Related codes
Same hardware involved
Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →