Error Check - Omron SYSDRIVE 3G3JV User Manual

Communications
H Error Check
• The CRC-16 check code is the remainder (16 bits) when all of the message blocks from the Slave
address to the final communications data are connected in series, as shown in the following diagram,
and this data is divided by a fixed 17-digit binary number (1 1000 0000 0000 0101).
8 bits
Slave address
Function code
Start of communications data
End of communications data
7-12
The LSB of the Slave address is handled as the MSB in CRC-16 calculation.
Note 1. Normally "0" is used as the initial value for CRC-16 cal-
culations, but "–1" (16 bits all "1") is used here.
Note 2. The CRC-16 code is calculated with the LSB of the
Slave address handled as the MSB, and the final MSB
of the communications data handled as the LSB.
Note 3. Calculate the CRC-16 code for responses from the
Slave as well, and compare it with the CRC-16 code in
the response message.
Chapter 7