Hitachi WJ Series

Chapter 11 RS485 Communication
11-1-5
11.1.4 Message Configuration
 The command message sent from the master to the slave is called "Query", and the response
message from the slave is called "Response". The transmission format of "Query" and "Response"
is shown below.
Query
Response
Slave address
Slave address for checking
Function code
Function code for checking
Query data
Response data
Error checking (CRC-16)
Error checking (CRC-16)
■ (1) Slave address (communication node address)
 The slave address is a number in the range of 1 to 247 set in advance for each inverter (slave).
(The query is fetched only by the inverter that matches the slave address of the query.)
 If "0" is specified as the slave address of the destination on the master side, broadcast to all
stations can be performed. For broadcast, all slaves receive data, but do not return a response.
 During broadcast, data cannot be read or looped back.
 In Modbus specification, the slave address is 1 to 247. However, if slave addresses 250 to 254
are used on the master side, broadcasting can be performed only for a specific slave address.
(Slaves do not respond, and broadcast is valid only for write commands (05h, 06h, 0Fh, 10h).)
Slave address
Destination
250 (FAh)
Broadcast to slave addresses 01 to 09
251 (FBh)
Broadcast to slave addresses 10 to 19
252 (FCh)
Broadcast to slave addresses 20 to 29
253 (FDh)
Broadcast to slave addresses 30 to 39
254 (FEh)
Broadcast to slave addresses 40 to 247
■ (2) Function code
 The function executed by the inverter is specified by the function code.
 The corresponding function code is shown below.
Function code
Function
Max. data bytes
handled by 1 massage
Max. number of data
handled by 1 message
01h
Read coil status
4
32 coils (in bits)
03h
Read multiple registers
32
16 registers (in bytes)
05h
Write coil
2
1 coil (in bits)
06h
Write holding registers
2
1 register (in bytes)
08h
Loop-back Test
-
-
0Fh
Write multiple coils
4
32 coils (in bits)
10h
Write multiple registers
32
16 registers (in bytes)
17h
Read/write multiple holding
registers
32/32
16/16 registers (in bytes)
A