What the 0x42 alarm means

Joint 2 reached its positive limit zone; the alarm auto-resets when the joint moves back out of the zone. In our Dobot service archive this alarm on Magician / MG400 / M1 / CR (DobotStudio) systems shows up constantly, and the first on-site inspection almost always locates it.

Most common causes

  • Program or jog drove joint 2 to the positive end of travel
  • Taught point at the limit
  • Payload pulling the arm into the limit
  • Frame or offset error
Field note: The first cause is the most common in the field — check it first, then work through the rest.

Step-by-step field fix

  1. Jog joint 2 back down out of the limit zone — auto-reset
  2. Re-teach points at the limit with margin
  3. Check payload settings
  4. Verify frames and offsets
  5. Re-test the path slowly
Safety first: For Dobot 0x42, this alarm family points at arm motion control: after a reset the arm can move unexpectedly, and anyone inside the working envelope is at strike and pinch risk. The self-serviceable action is Jog joint 2 back down out of the limit zone — auto-reset; anything past that falls under the arm working envelope and needs a certified engineer.

How we diagnose motion alarms on site

Dobot 0x42 belongs to the motion & path family. On Dobot 0x42 the failing stage is joint-integrated drive modules (collaborative models dominate) on the Dobot controllers (CR / MG / Nova series companions) - the gap between command and execution: trajectory planning, joint limits, singularities, following error and mechanical resistance. We start reading Dobot 0x42 at DobotStudio / app alarm messages; error codes are hexadecimal with a 0x prefix.

The chain involved in Dobot 0x42 runs: program command -> trajectory planner -> joint targets -> servo execution -> actual position feedback -> deviation compare.

If Program or jog drove joint 2 to the positive end of travel on Dobot 0x42 comes with a feeling of drag, the direction is clear: Following error that stays high on one axis only is usually rising mechanical resistance, not a weak servo. We turn the axis by hand with the brake released to feel smoothness, and listen to the reducer for once-per-revolution knocking - a single tick per turn on an RV reducer usually means internal bearing or cycloid damage. Grease that is black, dry or carries metal powder is the plainest evidence. Left alone, this graduates from a motion alarm to a scrapped reducer.

Field notes on this page cover Dobot 0x42 (Joint 2 Positive Limit Reached); written by the Henghuan repair team, updated 2026-10-01.

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Related Motion & Path alarms

0x20 — Inverse Kinematics Singularity 0x21 — Inverse Kinematics No Solution — Out of Workspace 0x22 — Inverse Kinematics Over Joint Limit 0x30 — Joint 1 Overspeed 0x31 — Joint 2 Overspeed 0x32 — Joint 3 Overspeed
Same family: this code belongs to the Motion & path alarms family - the page collects all Motion & path-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for FANUC · KUKA · ABB and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Dobot 0x42 alarm mean?

Joint 2 reached its positive limit zone; the alarm auto-resets when the joint moves back out of the zone. In our Dobot service archive this alarm on Magician / MG400 / M1 / CR (DobotStudio) systems shows up constantly, and the first on-site inspection almost always locates it. Dobot 0x42 sits in the motion & path family; on our work orders the highest-frequency trigger for this code is "Program or jog drove joint 2 to the positive end of travel".

QCan I clear a Dobot 0x42 alarm myself?

Whether Dobot 0x42 clears on its own depends on the outcome of "Jog joint 2 back down out of the limit zone — auto-reset". Finish the flow with "Re-test the path slowly" to confirm Dobot 0x42 - do not skip it. If that step is clean, the second most frequent cause on Dobot 0x42 is "Taught point at the limit". Two attempts and still there means stop: Dobot 0x42 involves the arm working envelope, and running Dobot 0x42 on can turn a repairable fault into a replacement.

QFor motion alarms like Dobot 0x42, can you triage remotely first?

The commonest causes we see on Dobot 0x42 are "Program or jog drove joint 2 to the positive end of travel, Taught point at the limit, Payload pulling the arm into the limit", so we stock the van against those. For Dobot 0x42 specifically, we carry mechanical and configuration items: grease, limit switches, drag-chain segments, encoder cables and the parameter sheets for common reducers. For Dobot 0x42, motion alarms can often be narrowed remotely first, so an on-site visit is not always immediate. Before we roll, tell us what Dobot 0x42 shows on DobotStudio / app alarm messages; error codes are hexadecimal with a 0x prefix and what the machine was doing - phone or video triage is free.

This page on Dobot 0x42 was compiled from actual repair records of the Henghuan Robotics repair team. Alarm notes are our own summary for troubleshooting reference only and may vary with controller and software version — please consult Dobot documentation or contact us if in doubt. Henghuan is an independent service provider, not affiliated with or endorsed by Dobot.