What the SRVO-068 alarm means

Serial data communication between the servo amplifier and the pulse coder failed or is severely disturbed. We are very familiar with this alarm on FANUC R-30iA / R-30iB / R-30iB Plus systems — usually the first on-site inspection is enough to confirm the cause.

Most common causes

  • Encoder cable damaged or connector loose (most common)
  • Severe electrical noise (poor grounding, welding machines nearby)
  • Pulse coder internal failure
Field note: Our ticket data shows the first cause is by far the most common — start there to avoid dead ends.

Step-by-step field fix

  1. Reseat encoder connectors at both motor and controller ends
  2. Inspect the encoder cable along its full length, especially flex points
  3. Check grounding of the robot and controller
  4. If cable and grounding are good, replace the pulse coder (motor)
Safety first: For FANUC srvo-068, amplifiers and boards are live parts: hot-plugging a board burns interface circuits, and body static can kill sensitive devices. The self-serviceable action is Reseat encoder connectors at both motor and controller ends; anything past that falls under live boards and power devices and needs a certified engineer.

How we diagnose amplifier/hardware alarms on site

FANUC srvo-068 belongs to the amplifier & hardware family. On FANUC srvo-068 the failing stage is alpha-i / beta-i servo amplifiers with PSM supply modules and SVM servo modules (SPM where spindles fit) on the R-30iB Plus / R-30iB Mate Plus / R-30iA - the amplifier and drive hardware itself plus its periphery: boards, fuses, cooling, supply, connectors and self-test. We start reading FANUC srvo-068 at the iPendant ALARM screen (SRVO / MOTN / SYST / INTF prefixes) together with the amplifier's 7-segment status code.

The chain involved in FANUC srvo-068 runs: control-side signal -> amplifier board (drive and sense circuits) -> fuses and supply -> cooling -> motor-side output.

On FANUC srvo-068 record two codes, not one: The amplifier's own status code is usually finer than the controller's message. The controller may raise one generic servo alarm while the two-digit code on the amplifier points straight at the stage - overcurrent, overvoltage, over-temperature or feedback fault. We log both codes together and read them against each other; that pairing is far more accurate than either alone. On some models the panel code only refreshes after a power cycle, which is worth remembering.

Field notes on this page cover FANUC srvo-068 (DTERR - Data Transmission Error); written by the Henghuan repair team, updated 2026-10-01.

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Related Amplifier & Hardware alarms

SRVO-057 — FSSB Disconnect SRVO-069 — CRCERR - CRC Error SRVO-071 — SPHAL - Soft Phase Alarm SRVO-072 — PMAL - Pulse Coder Phase Alarm SRVO-073 — CMAL - Pulse Coder Count Error SRVO-074 — LDAL - Pulse Coder LED Alarm
Same family: this code belongs to the Amplifier & hardware alarms family - the page collects all Amplifier & hardware-family codes we have handled, with the common inspection order and spares.
Other brands: see our KUKA, ABB, Yaskawa and Universal Robots field-fix libraries — or the full 10-brand hub.

Frequently asked questions

QWhat does the FANUC srvo-068 alarm mean?

Serial data communication between the servo amplifier and the pulse coder failed or is severely disturbed. We are very familiar with this alarm on FANUC R-30iA / R-30iB / R-30iB Plus systems — usually the first on-site inspection is enough to confirm the cause. FANUC srvo-068 sits in the amplifier & hardware family; on our work orders the highest-frequency trigger for this code is "Encoder cable damaged or connector loose (most common)".

QCan I clear a FANUC srvo-068 alarm myself?

Whether FANUC srvo-068 clears on its own depends on the outcome of "Reseat encoder connectors at both motor and controller ends". Finish the flow with "If cable and grounding are good, replace the pulse coder (motor)" to confirm FANUC srvo-068 - do not skip it. If that step is clean, the second most frequent cause on FANUC srvo-068 is "Severe electrical noise (poor grounding, welding machines nearby)". If FANUC srvo-068 returns after two clears, or the checks point at Encoder cable damaged or connector loose (most common), stop the cell and call a professional robot repair engineer.

QFor hardware alarms like FANUC srvo-068, does it always mean an expensive part swap?

The commonest causes we see on FANUC srvo-068 are "Encoder cable damaged or connector loose (most common), Severe electrical noise (poor grounding, welding machines nearby), Pulse coder internal failure", so we stock the van against those. For FANUC srvo-068 specifically, we carry fuses, filter mats, common connectors and terminals; boards are stocked by type or go through the repair channel. For FANUC srvo-068, on hardware alarms we inspect before quoting - we do not open with replace the power stage. Before we roll, tell us what FANUC srvo-068 shows on the iPendant ALARM screen (SRVO / MOTN / SYST / INTF prefixes) together with the amplifier's 7-segment status code and what the machine was doing - phone or video triage is free.

This page on FANUC srvo-068 was written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your FANUC documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by FANUC.