Error Message Ratio


Thread Starter

Hung Lam

If a Modbus RTU device makes 5 to 8% error message by CRC frame check, it is normal or bad for a multi-drop network with baudrate 9600bps?

Could anyone classify the percentage of error message for good, standard and bad communication.


Hung Lam

Michael T Mellish

Your error rate is high indicating three possible problem areas:

1. Your driver is not always correctly calculating the CRC-16 so some messages are rejected.

2. Your host is issues new commands before a response is received. These additional characters are crammed into the modbus slaves serial port buffer, overwriting parts of the uncomplete message (so it is corrupted & failes CRC check)

3. You have communications cabling issues which are disrupting the proper data flow.

A clean installation will run less than 1% errors.