What the SEG-4 alarm means

On CS8/CS8C the controller front 7-segment display shows '4': the amplifier drive-enable (DF) contact on J112 is open — the power stage refuses to enable one or more drives. This is one of the faults our repair team handles on Staubli CS8 / CS9 (VAL3) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • E-stop chain or guard interlock holding the DF loop open
  • Drive fault on one axis latching the DF contact open
  • Wiring fault between drives and RSI
  • STARC board fault
Field note: the first item on this list is what we find most often on real machines. Check it before you go deeper.

Step-by-step field fix

  1. Open Control Panel > Controller Status on the pendant to read which drive is flagged
  2. Check the event history for the amplifier number and the detailed fault
  3. Verify the E-stop chain and all guard interlocks are closed
  4. Check wiring between the drives and the RSI board
  5. If no individual drive is faulty, test the STARC board before swapping drives
Safety first: never bypass safety circuits or force contactors closed. If the alarm involves E-stop chains, brakes or drive power, and you are not a trained robot technician, contact a professional — wrong moves here can cost you a robot or an injury.

Still stuck? Get an engineer on the phone — right now

Tell us the alarm code, the robot model and what was happening when the alarm came up. Our engineers run these diagnostics every day, and remote diagnosis by phone or video call is free.

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Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Drive & Power Stage alarms

DCBusUV — DC Bus Undervoltage at Power-Up (Pre-charge Failure) 24VExt — External 24V Supply Fault (Safety System Dropout) OverTemp — Drive / Cabinet Overtemperature
Other brands: we also keep field-fix libraries for Epson · Nachi · Omron and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Staubli SEG-4 alarm mean?

On CS8/CS8C the controller front 7-segment display shows '4': the amplifier drive-enable (DF) contact on J112 is open — the power stage refuses to enable one or more drives. In field practice it belongs to the drive & power stage family of faults.

QCan I clear a Staubli SEG-4 alarm myself?

Sometimes. Work through the step-by-step checks on this page — the first listed cause is what we find most often in the field. If the alarm returns after two attempts, or the fault involves power, brakes or safety circuits, stop and call a qualified robot service engineer.

QHow fast can a Henghuan engineer help?

On-site response in the Pearl River Delta within 30 minutes to 3 hours, across mainland China in 1-3 business days, and worldwide within 2-5 business days. Remote diagnosis by phone/WhatsApp/video is available immediately.

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 Staubli documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Staubli.