What causes fault code 60002 (PLC Communication Fault â€” Serial Link Down)?

Serial cable disconnected or pins bent in DB9/DB25 connector. Baud rate or parity mismatch after parameter change on one end. RS-485 termination resistor missing or wrong value on bus end. Serial port on PLC or device has hardware failure. Electrical noise on serial line from nearby VFD or motor power cables

How do I fix fault code 60002?

Reseat serial cable at both ends â€” inspect for bent or broken pins. Verify communication parameters match at both ends: baud rate, parity, stop bits, station address. Check RS-485 termination â€” 120 ohm resistor required at each physical end of the bus. Route serial cable away from power cables and VFD wiring â€” 6 inch minimum separation. Substitute serial cable with known-good cable to rule out cable failure. Test with serial monitor software on laptop to confirm data is being sent/received

PLC Communication Fault â€” Serial Link Down

60002

Serial communication link (RS-232/RS-485) between PLC and device has failed. Data exchange stopped.

high general conveyor piler asrs packaging palletizer

plc communication serial rs485 rs232

Probable Causes (ranked)

Serial cable disconnected or pins bent in DB9/DB25 connector
Baud rate or parity mismatch after parameter change on one end
RS-485 termination resistor missing or wrong value on bus end
Serial port on PLC or device has hardware failure
Electrical noise on serial line from nearby VFD or motor power cables

Fix Steps

1 Reseat serial cable at both ends â€” inspect for bent or broken pins
2 Verify communication parameters match at both ends: baud rate, parity, stop bits, station address
3 Check RS-485 termination â€” 120 ohm resistor required at each physical end of the bus
4 Route serial cable away from power cables and VFD wiring â€” 6 inch minimum separation
5 Substitute serial cable with known-good cable to rule out cable failure
6 Test with serial monitor software on laptop to confirm data is being sent/received

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.

Need a deeper diagnosis with photo analysis and AI-powered troubleshooting?

Run Full Diagnosis