Mitsubishi MDS alarm 2E means the motor side encoder (connected at CN2) detected an error — ‘main side encoder: error 4’. On linear motor axes this includes the linear scale. The encoder's own diagnostics flagged a fault; the drive relays it. Mitsubishi's manual is brief here for a reason: the details differ for each encoder model, so the manual routes you to the alarm 1B investigation items and the ‘Encoder alarm’ section for the specific encoder fitted.
How to work a 2E
- Identify the encoder model first — the OSA-series rotary encoder or linear scale type on this axis — because the error-4 meaning is encoder-specific. The encoder alarm section for that model tells you whether error 4 is contamination, internal circuit, over-speed or something else.
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Work the standard encoder-fault sequence (the alarm 1B items) — in practice the same discipline as the whole encoder family:
- Reseat and inspect the CN2 connectors (drive and encoder ends).
- Inspect and meter the encoder cable, flexing at suspect points.
- Swap-test to split drive vs encoder — the alarm follows the guilty side.
- Environment: grounding and cable shielding for intermittent cases.
- Linear axes: a 2E that appeared after coolant flooding or crash points at the scale — contamination on the glass/tape or a damaged read head; scales are cleanable/serviceable, but by procedure, not with a rag.
Tip: 2E vs its neighbour 2F: 2E = the encoder itself reports an internal error; 2F = the drive cannot talk to the encoder cleanly. 2E leans encoder/scale; 2F leans cable, routing and grounding. Both end at the same hardware family — but they start the hunt at opposite ends of the wire.
Related guides
- Mitsubishi MDS alarm 2F (encoder communication error)
- Mitsubishi MDS alarm 18 (initial communication error)
- Mitsubishi MDS alarm 25 (absolute position lost)
2E on a rotary encoder or linear scale? JJ Automation stocks Mitsubishi encoders, services linear scales, and swap-tests drive vs encoder on site in NCR. WhatsApp us or call +91 88262 07004.