What is CRC Error?

A Cyclic Redundancy Check (CRC) error is an error-detecting code used to identify accidental changes to raw data in digital networks and storage devices.

Cyclic Redundancy Check (CRC) Error indicates when data is corrupted. Calculating from all data, CRC validates packets of information sent by devices and verifies it against the data extracted, ensuring its accuracy. When sending packets over, BACnet automatically calculates and stores a CRC value for the packet. Later when the packet is received, BACnet calculates the CRC value of the packet and compares it to the original value. If the two values do not exactly match a CRC error occurs.

How CRC Occurs

There are many reasons a CRC error can occur. One of the most common reasons for this error is a packet error, which occurs when network communications are bad or go in and out. This creates vulnerability for invalid data to be placed into the file. Some other possible reasons are exposure to noise and poor wiring.

Signs of CRC Error

Since this error can be imperceptible, evidence of this error exists when the user notices information packets being dropped, the meter not showing up online or information is stale and not updating.

CRC errors can occur due to various reasons, such as:

• Transmission Errors: Noise or interference during data transmission.
• Storage Errors: Bad sectors on a hard drive or issues with storage media. 

Fixing CRC Error
To ensure this error doesn’t happen again, run Wireshark or MS/TP sniffer to capture packets being sent and received.

1. Take capture of packets (several hundred frames) and import to Wireshark
2. Ensure that the CRC byte matches/ adds correctly, if not there is still a CRC Error.

CLICK HERE to learn more about troubleshooting BACnet.