YASKAWA Varispeed G7, Modbus Communication Manual

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Write Single Register – Function Code 06H
The Write Single Register function allows the writing of data to one register only.
Write Single Register Command Message
Table 2.5 Write Command Message
Description Data
Slave Address 01h
Function Code 06h
Upper 00h
Register Address
Lower 01h
Upper 00h
Data
Lower 03h
Upper 98h
CRC-16
Lower H0B
Each G7 drive slave address is set via parameter H5-01. Valid slave addresses must be in the range of 1 ~ 20 hex (1 ~ 32 dec) and entered as a
hexadecimal number. No two slaves may have the same address. The master addresses the slave by placing the slave address in the Slave
Address field of the message. In the command message above, the slave is addressed at 01h. Broadcast address 0 is valid for register write
commands.
By setting the slave address to zero (0) in the command message, the master can send a message to all the slaves on the network simultaneously.
This is called simultaneous broadcasting. In a simultaneous broadcast message there is no response message.
The function code of this message is 06h (write single register).
In the command message above the register address is 01h (0001h).
The data section contains the data to be written.
A CRC-16 value is generated from a calculation including the message slave address, function code, starting register, quantity, Number of Data
Bytes, and all register data. The procedure for calculating a CRC-16 is described at the end of this chapter. When the slave receives the
command message it calculates a CRC-16 value and compares it to the CRC-16 of the command message. If the two CRC-16 values are
identical and the slave address is correct, the slave processes the command message. If the two CRC-16 values are not identical, the slave will
discard the command message and not respond.
If the command message has a valid slave address, function code, register address and data, the slave will respond with a normal response
message. If the command message has an invalid function code, register address and/or data, the slave will respond with a fault response
message. If the command message has an invalid slave address or CRC-16, no response will be returned.