What causes fault code 50004 (VFD Fault â€” Communication Loss)?

Network cable disconnected or damaged between PLC and VFD. VFD network module crashed â€” needs power cycle. PLC communication module overloaded â€” too many nodes or scan rate too fast. Network switch or hub failure in the path between PLC and VFD. VFD station/node address changed or duplicated on network

How do I fix fault code 50004?

Check network cable at VFD communication port â€” reseat connector. Verify network switch or hub between PLC and VFD â€” check power and link LEDs. Power cycle the VFD to reset communication module. Verify VFD node/station address matches PLC configuration â€” check for duplicate addresses. If using Profinet/EtherNet-IP, ping VFD IP address from laptop to confirm network path. Check PLC communication module status for error counters or diagnostic codes

VFD Fault â€” Communication Loss

50004

VFD lost communication with PLC over fieldbus network. Drive stopped or went to fault safe state.

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vfd drive communication network fieldbus

Probable Causes (ranked)

Network cable disconnected or damaged between PLC and VFD
VFD network module crashed â€” needs power cycle
PLC communication module overloaded â€” too many nodes or scan rate too fast
Network switch or hub failure in the path between PLC and VFD
VFD station/node address changed or duplicated on network

Fix Steps

1 Check network cable at VFD communication port â€” reseat connector
2 Verify network switch or hub between PLC and VFD â€” check power and link LEDs
3 Power cycle the VFD to reset communication module
4 Verify VFD node/station address matches PLC configuration â€” check for duplicate addresses
5 If using Profinet/EtherNet-IP, ping VFD IP address from laptop to confirm network path
6 Check PLC communication module status for error counters or diagnostic codes

Suggested Replacement Parts

Parts matched to fault category: Network Module

Allen-Bradley 1756-EN2T EtherNet/IP Module P/N: 1756-EN2T ControlLogix EtherNet/IP module, dual port, DLR capable

Amazon $850.00 Grainger $1050.00

Siemens CM 1542-1 PROFINET Module P/N: 6GK7542-1AX00-0XE0 S7-1500 PROFINET IO controller, 2-port switch

Amazon $650.00 Mouser $720.00

Managed Industrial Ethernet Switch 8-Port P/N: SE2-SW5U 8-port managed switch, DIN rail, 10/100 Mbps, IGMP snooping

AutomationDirect $145.00 Amazon $120.00 Mouser $155.00

Prices are estimates. Verify part numbers match your equipment before ordering.

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