Mitsubishi S01, S03 and S04 alarms: start with the reset category

After a servo alarm appears, whether pressing reset clears it is not the only question. The category describes the conditions under which the system handles the abnormality; the cause still requires the complete number, axis name and drive model. The following is limited to the classification in M800/M80/E80/C80 handbook IB-1501280-B, not all Mitsubishi products.

The three categories in the manual

Page 29 specifies that, after eliminating the cause, S01 corresponds to PR, switching NC power on again; S03 to NR, the NC reset key; and S04 to AR, switching both NC and drive-unit power on again. Eliminating the cause is a prerequisite in every case. The final two characters of a servo alarm number relate to the two-character display on the drive-unit front; detailed troubleshooting still requires the matching drive manual.

Reading a complete alarm

First record four items: category, alarm text, axis name and complete number. Add a separate column for the drive-panel display and module model. If several axes appear on the controller, match them individually rather than applying the first alarm's code to all drives. Mark unclear panel displays or axis names inconsistent with drawings as unconfirmed instead of filling gaps arbitrarily.

For example, identical final characters during two stoppages still require separate checks if the alarm prefix, affected axis or hardware series differs. Preserve leading zeros and letters when consulting tables; do not mistake letter B for digit 8. A full-screen photograph is easier to verify than a verbal description and helps distinguish current alarms from older records.

Handover before resetting

• Identify who established the cause, what action was taken and what remains unfinished. “Tried resetting” does not show that checks are complete.
• Confirm current mechanical position, tool and workpiece condition, and the operating conditions to restore after the stoppage, following the machine builder's requirements.
• If power must be cycled, use the machine's normal shutdown and restart procedure; do not create a power interruption by arbitrarily unplugging modules.
• After reset, record remaining or recurring alarms and the action underway. Temporary disappearance must not be documented as a completed repair.

When repair personnel should continue the assessment

If alarms recur or accompany tripping, unusual odours or visible module abnormalities, stop repeated attempts and hand over for inspection. Electrical disassembly, release of stored energy and axis movement cannot be performed solely from this category list. The article helps interpret messages; it does not replace the relevant drive-unit fault procedure.

To organize verifiable site information, see Mitsubishi alarm screenshot records. The 006B inrush-circuit abnormality case gives a particular S01 example; its observed symptoms are not the cause of every S01 alarm.

Reference: M800/M80/E80/C80 Series HANDBOOK, IB-1501280-B, §3.1, printed page 29; power-supply alarm table on page 39; MCP alarms on page 48. This text explains scope and suggests ways to organize site records. Follow the documentation for the actual system and machine builder for specific operations.