Omron SYSDRIVE 3G3RV, User Manual

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Communications Functions
6-
81
Slave Address
Set
the Inverter address from 0 to 32. If you set 0, commands from the master will be broadcast (i.e., the
Inverter
will not return responses).
Function Code
The
function code specifies commands. There are three function codes, as shown below.
Data
Configure
consecutive data by combining the storage register address (test code for a loopback address) and
the
data the register contains. The data length changes depending on the command details.
Error Check
Errors
are detected during communications using CRC-16. The CRC-16 data is the remainder of dividing all
of
the message data blocks as a continuous string of data by a specific binary number (1 1000 0000 0000
0101),
as shown in the following diagram.
Fig 6.59
Function Code
(Hexadecimal)
Function
Command Message Response Message
Min. (Bytes) Max. (Bytes) Min. (Bytes) Max. (Bytes)
03H Read
storage register contents
8 8 7 37
08H Loopback
test
8 8 8 8
10H Write
multiple storage registers
11 41 8 8
8 bits
When calculating the CRC-16 data, the LSB of the slave ad-
dress is treated as the MSB.
Slave address
Function code
Start of communications
data
End of communications
data
Note 1. Although normally the initial value for the CRC-16 calculation is 0, “-1”
(all 16 bits set to 1) is used here instead.
2. The CRC-16 data is calculated using the LSB of the slave address as
the MSB and the last MSB of the communications data as the LSB.
3. Calculate the CRC-16 data for the response message from the slave
and verify that it is the same as the one in the response message.