Demag E-701: Demag DR-PRO 50t Error Code E-701

Symptoms

The crane HMI displays E-701, indicating a travel limit switch fault. The trolley or bridge travel limit switch has been activated or has failed its function check. The affected travel direction is disabled to prevent collision with end stops or other equipment.

Possible Causes

Travel limit switch physically activated by reaching the end of travel
Limit switch cam or actuator misaligned or damaged
Limit switch electrical contact welded or failed
Limit switch wiring fault or connector loose

Troubleshooting Steps

Step 1: Check if the crane or trolley has reached the physical end of travel
If at the end of travel, move in the opposite direction to clear the limit switch
Step 2: Inspect the limit switch cam and actuator for proper alignment
Adjust cam position or replace if damaged
Step 3: Test the limit switch contacts with a multimeter for proper open/close
Replace switch if contacts are welded or not functioning
Step 4: Check wiring continuity from the switch to the control panel
Repair any broken wires and tighten loose connections

How to Reset

To reset E-701: 1) Move the crane or trolley away from the limit position. 2) On the HMI, acknowledge the limit switch fault. 3) Press Reset. 4) The travel system performs a function check. 5) If the limit switch operates correctly, travel is re-enabled.

Common Replacement Parts

DM-50-001: Travel limit switch, heavy-duty, 2NO+2NC (Test weekly by approaching the end of travel)
DM-50-005: Limit switch cam, adjustable type (Verify cam angle and tightness monthly)
DM-50-010: Switch wiring harness, 5-conductor (Inspect for damage during quarterly maintenance)

Frequently Asked Questions

Q: How do I test travel limit switches?
Test weekly by slowly jogging the crane or trolley toward each end of travel. The crane should stop automatically when the limit switch is activated. If the crane does not stop, immediately jog in the opposite direction and investigate the switch, cam, and wiring before resuming operation.
Q: What causes limit switch failures?
Limit switches fail due to physical damage from impact, water or dust ingress, mechanical wear of the actuator mechanism, electrical contact welding from frequent high-current operation, or wiring degradation from vibration. Use heavy-duty rated switches and inspect regularly in harsh environments.

Demag DR-PRO 50t Error Code E-701