Hitachi SJ700B SERIES, Instruction Manual

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Chapter 4 Explanation of Functions
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The formats of the query and response frames are described below.
Message configuration: Query
Header (silent interval)
Slave address
Function code
Data
Error check code
Trailer (silent interval)
(i) Slave address
The slave address is a number 1 to 32 that is assigned to the inverter (slave) beforehand. (A query is
received by the inverter having the same slave address as that specified in the query.)
The query with the slave address set to "0" is broadcasted to all the connected inverters.
With a broadcast query, the master system can neither read inverter data nor perform a loopback test.
(ii) Data
The data contains a functional instruction.
The SJ700 series inverter supports the following Modbus data format:
Data name Description
Coil data 1-bit binary data that can be referenced and changed
Register data 16-bit data that can be referenced and changed
(iii) Function code
The function code specifies the function to be executed by the inverter.
The table below lists the function codes supported by the SJ700 series inverter.
Function codes
Function code Function
Maximum number of data
bytes in a message
Maximum data count in a
message
01h Reads the coil status. 4 32 coils (in units of bit)
03h Reads registers. 8 4 registers (in units of byte)
05h Writes data to a coil. 2 1 coil (in units of bit)
06h Writes data to a register. 2 1 register (in units of byte)
08h Performs a loopback test. -
0Fh Writes data to multiple coils. 4 32 coils (in units of bit)
10h Writes data to multiple registers. 8 4 registers (in units of byte)