What the 4780 alarm means

The Functional Safety Unit (FSU) on the YRC1000 detects that the robot exceeded a configured safety limit — position range, speed, or orientation — and initiates a safe stop. Codes 4780-4799 are all FSU alarms. This is one of the faults our repair team handles on Yaskawa DX100 / DX200 / YRC1000 systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Robot jogged or played back into a forbidden zone defined in the safety settings
  • Speed limit for manual/reduced mode exceeded
  • Safety file out of sync after a backup restore or file transfer
  • Tool calibration mismatch making the monitored TCP position wrong
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. Jog the robot back inside the permitted zone in joint mode
  2. Check the safety settings (zone limits, speed limits) against the cell layout
  3. Verify the TCP/tool calibration matches the real tooling
  4. Re-load a consistent safety file if the FSU data was corrupted
  5. Power-cycle once after correcting the settings; if FSU alarms persist, contact a qualified safety engineer
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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Related Safety Chain & E-Stop alarms

1219 — Enable Switch Sticking (DX100/DX200/YRC1000)
Other brands: we also keep field-fix libraries for Universal Robots · Kawasaki · Staubli and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Yaskawa 4780 alarm mean?

The Functional Safety Unit (FSU) on the YRC1000 detects that the robot exceeded a configured safety limit — position range, speed, or orientation — and initiates a safe stop. Codes 4780-4799 are all FSU alarms. In field practice it belongs to the safety chain & e-stop family of faults.

QCan I clear a Yaskawa 4780 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 Yaskawa documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Yaskawa.