Applicable Systems
Mitsubishi Elevator
Symptoms
Communication fault. Communication between controller boards has been interrupted.
Possible Causes
- Internal communication cable loose or damaged
- Communication board hardware fault
- Communication parameter mismatch between boards
- EMI affecting internal communication bus
Troubleshooting Steps
- Step 1: Check the equipment status and fault indicators to confirm the active fault code
Fault indicator or HMI displays code 31 as active - Step 2: Verify all electrical connections, wiring harnesses, and connector seating
All connections secure, no corrosion, loose pins, or damaged wires - Step 3: Check the communication cable continuity and connector seating at both ends
Cable continuity confirmed, connectors fully seated with locking tabs engaged - Step 4: Verify communication parameters (baud rate, node address, protocol) match network configuration
All communication parameters match the network setup - Step 5: Inspect cable for EMI interference: check routing away from high-voltage lines and motor cables
Cable routed away from EMI sources, shielding intact - Step 6: Check terminating resistors at bus endpoints if applicable (e.g., PROFIBUS, CANopen)
Terminating resistors installed at both bus ends - Step 7: Reset the fault after restoring communication: power-cycle the affected node
Communication restores and fault clears
How to Reset
To reset: 1) Fix the communication cable or parameter issue. 2) Power-cycle the affected node. 3) Verify communication restores. Caution: Check all nodes on the bus.
Frequently Asked Questions
- Q: What does fault code 31 mean on the Mitsubishi Mitsubishi Elevator?
Fault 31 indicates a communication fault. The equipment has lost communication with a connected device or network. Check the communication cables, connectors, and network parameters.
- Q: Can I continue operating the equipment with fault 31 active?
No. The equipment has detected a fault condition and has taken protective action (typically stopping or derating). Continuing to operate without fixing the root cause may cause further damage. Always investigate and fix the fault before resuming operation.
Source: Mitsubishi Elevator Controller F-Board Diagnostic Manual, Mitsubishi Electric Documentation
Category: Elevator