Error Check; Total Communication Time; Normal Response - Omron 3G3MX2 User Manual

Error Check

CRC (Cyclic Redundancy Check) is used for the Modbus communication (Modbus-RTU) error
check.
The CRC code is a 16-bit data generated against the block of random length data in the 8-bit
unit. Generation of CRC codes uses the generation polynomial "CRC-16 (X
<CRC-16 Calculation Example>
CRC-16 operator
CRC = FFFFh
Target data
Swap the Hi and Lo bytes of CRC.
Completed

Total Communication Time

The time from receiving query to the response by the Inverter will be the total of <the silent
interval (3.5-character length) and C078 (communication wait time) setting>.
If sending another query to the Inverter after receiving the response, be sure to provide the
silent interval length (3.5 characters) at the minimum.

Normal Response

If the Parameter No. in the query indicates a loop-back (08h), writing to a coil(s) (05h/0Fh) or
writing to a holding register(s) (06h/10h), the Inverter returns a response whose content is the
same as the query.
If the Parameter No. in the query indicates reading from a coil (01h) or reading from a holding
register (03h), a response is returned whose slave address and Parameter No. are the same
as the query and to which data has been added.
Refer to the format for each query specified below.
SYSDRIVE MX2 Series USER'S MANUAL (3G3MX2-A@@@@)
6-4 Modbus Communication (Modbus-RTU) Protocol
CRC
CRC register (2 bytes)
Yes
CRC = CRC XOR target data
Target data
completed
CRC = CRC is shifted to
0
Overflowed bit due to
CRC = CRC is shifted to
Shift the applicable data by 1 byte.
Hi Lo
Completed
8-bit shift
Remaining bit
the right by 1 bit.
the shift
1
the right by 1 bit.
16 15 2
+ X + X + 1)".
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