What do CRC errors (1465) indicate.

Issue

Site experiencing comm issues on the Infinet or MSTP bus.

Controller error logs show many 1465 (Cyclical Redundancy Check) errors.

Product Line

Andover Continuum

Environment

  • Infinet
  • MSTP
  • b3
  • i2
  • Controller error log

Cause

CRC errors are check sum errors.

Before a packet is sent, the sending controller calculates a checksum based on the packets contents.

This checksum is then appended to the packet.

When the packet is delivered, the receiving controller calculates it's own checksum based on the packets contents.

If the check sums do not equal, this indicates that somewhere in the delivery process the packet has been altered, usually due to bad cable or connections, controller grounding, or a bad controller transceiver.

For additional information on troubleshooting the infinet or mstp bus, see Lessons Learned Article #5820.

Resolution

CRC errors usually indicate poor signal integrity on the physical bus. Infiltration of "noise" on the comm cable due to the presence of high voltage conductors, radio transmissions, etc. In some cases a failed transceiver may be involved but this is generally not the case. Poor controller grounding can also contribute to this issue.

Generally CRC errors call for using a scope to assess the signal integrity on a bus.