ERR_INVALID_PACKET_CRC
Received packet has invalid CRC
Allen-Bradley · MicroLogix 1400 Programmable Controllers
What does ERR_INVALID_PACKET_CRC mean?
A received Modbus TCP packet contained an invalid Cyclic Redundancy Check (CRC) in its data portion. This indicates data corruption during transmission or an improperly formed packet from the sender.
Common Causes
- Network interference or noise corrupting data during transmission.
- Faulty network hardware (cables, switches, network interface card).
- Remote Modbus TCP client sending malformed packets due to software or configuration error.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Check the integrity of network cabling and connections between the controller and the remote device.
- 2
Verify the remote Modbus TCP client is sending correctly formatted Modbus TCP packets.
- 3
Inspect network hardware for faults and ensure proper grounding.
- 4
Monitor network traffic with a protocol analyzer to identify the source of corruption.
Verified technical data. Last updated: March 2026
Related Faults
Source: Allen-Bradley MicroLogix 1400 Programmable Controllers