What the 34200 alarm means

The computer unit lost the drive communication bus entirely — every axis is offline and the robot cannot move. This is a fault we handle frequently on ABB IRC5 / OmniCore (RobotWare) systems — in most cases we can pin down the root cause on the first site visit.

Most common causes

  • Drive unit main power missing (breaker, fuses, incoming supply)
  • Faulty drive communication cable or node
  • Computer unit or drive unit hardware failure
  • Blown cabinet fuses after a supply disturbance
Field note: The first item on this list is what we hit most often on real machines — clear that one before going deeper.

Step-by-step field fix

  1. Check the drive unit LEDs and cabinet supply breakers/fuses
  2. Measure incoming three-phase power at the cabinet
  3. Reseat the drive communication cables
  4. Power-cycle the controller; if the bus stays down, isolate computer unit vs. drive unit by swap or service diagnostics
Safety first: For ABB 34200, this alarm family involves the DC bus, which sits at several hundred volts and stays charged for minutes after power-off - touching terminals is a shock hazard. On site you may not carry out the first step yourself: Check the drive unit LEDs and cabinet supply breakers/fuses. Beyond that it is the DC bus and power stage work - leave it to a professional. On ABB 34200: checking incoming voltage at the disconnect and looking at breakers and fuses is fine to do yourself; opening the cabinet to touch bus terminals or pulling power modules needs a qualified electrician.

How we diagnose drive alarms on site

ABB 34200 belongs to the drive & power stage family. On ABB 34200 the failing stage is DSQC drive modules (DSQC 600 generation; OmniCore drive units) on the IRC5 / OmniCore - the fault sits on the energy chain: mains input, rectification, DC bus, braking resistor, inverter power devices and the drive board. We start reading ABB 34200 at the FlexPendant event log and system diagnostics, with the cabinet status LEDs.

The chain involved in ABB 34200 runs: three-phase mains -> rectifier -> DC bus (bus capacitors) -> brake chopper / braking resistor -> inverter (IGBT) -> motor.

When ABB 34200 fires, the site usually reports Drive unit main power missing (breaker, fuses, incoming supply) first, but the real cause is often cooling: More than half of power-stage alarms are not a dead device but a device cooked by failed cooling. A stopped cabinet fan, a packed filter mat or a dusted air duct keeps IGBT junction temperature high: intermittent over-temperature first, hard fault days later. On these alarms we open the power module and look for cracked thermal paste and felted dust in the duct, then measure phase-to-phase output and insulation to frame. Swapping the module without cleaning the duct just buys the same failure again.

Field notes on this page cover ABB 34200 (Communication with All Drive Units Interrupted); written by the Henghuan repair team, updated 2026-10-01.

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Related Drive & Power Stage alarms

34316 — Motor Current Error 34251 — Missing Phase of Input Power 34400 — DC Link Voltage Too High
Same family: this code belongs to the Drive & power stage alarms family - the page collects all Drive & power stage-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for Yaskawa · Universal Robots · Kawasaki and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the ABB 34200 alarm mean?

The computer unit lost the drive communication bus entirely — every axis is offline and the robot cannot move. This is a fault we handle frequently on ABB IRC5 / OmniCore (RobotWare) systems — in most cases we can pin down the root cause on the first site visit. ABB 34200 sits in the drive & power stage family; on our work orders the highest-frequency trigger for this code is "Drive unit main power missing (breaker, fuses, incoming supply)".

QCan I clear a ABB 34200 alarm myself?

Whether ABB 34200 clears on its own depends on the outcome of "Check the drive unit LEDs and cabinet supply breakers/fuses". Finish the flow with "Power-cycle the controller; if the bus stays down, isolate computer unit vs. drive unit by swap or service diagnostics" to confirm ABB 34200 - do not skip it. If that step is clean, the second most frequent cause on ABB 34200 is "Faulty drive communication cable or node". Two attempts and still there means stop: ABB 34200 involves the DC bus and power stage, and running ABB 34200 on can turn a repairable fault into a replacement.

QFor drive/power alarms like ABB 34200, what spares do you bring on site?

The commonest causes we see on ABB 34200 are "Drive unit main power missing (breaker, fuses, incoming supply), Faulty drive communication cable or node, Computer unit or drive unit hardware failure", so we stock the van against those. For ABB 34200 specifically, we stock the van along the energy chain: braking resistors, bus capacitors, input fuses, drive-board supply parts and the common power modules for the brand. For ABB 34200, drive alarms usually stop the whole line, so they sit at the front of our dispatch queue. Before we roll, tell us what ABB 34200 shows on the FlexPendant event log and system diagnostics, with the cabinet status LEDs and what the machine was doing - phone or video triage is free.

This page on ABB 34200 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 ABB documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by ABB.