Omron SYSDRIVE MX2 SERIES User Manual

6-6
6-4 Modbus Communication (Modbus-RTU) Protocol
SYSDRIVE MX2 Series USER'S MANUAL (3G3MX2-Axxxx)
6
Communication Function
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
16
+ X
15
+ X
2
+ 1)".
<CRC-16 Calculation Example>
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.
CRC = FFFFh
CRC-16 operator
Target data
CRC = CRC XOR target data
8-bit shift
CRC = CRC is shifted to
the right by 1 bit.
Overflowed bit due to
the shift
Swap the Hi and Lo bytes of CRC.
Completed
CRC = CRC is shifted to
the right by 1 bit.
Hi Lo
CRC register (2 bytes)
CRC
Target data
completed
Yes
Completed
Remaining bit
0
1
Shift the applicable data by 1 byte.

Omron SYSDRIVE MX2 SERIES Specifications

General

Brand	Omron
Model	SYSDRIVE MX2 SERIES
Category	Inverter
Language	English