Hitachi WJ C1 Series

Chapter 11 RS485 Communication
11-1-1
11.1 Modbus-RTU
11.1.1 Communication Specifications and Setting Parameters
 What are the specifications of Modbus communication function?
 WJ-C1 inverters are equipped with RS-485 compliant Modbus-RTU port. They can communicate
with external control equipment devices. The basic specifications and setting parameters for
Modbus communication are as follows.
 When communication option board is installed, Modbus communication function of the main
unit cannot be used.
 In Modbus communication of WJ-C1, there are data with restrictions when accessing as "2
register length parameter" for large data that does not fit in 1 word. For details, refer to
"Exception code 27h" in "11.2.9 Exceptional Responses".
Item
Specifications
Remarks
Protocol
Modbus-RTU (Slaves)
Baud rate
2400/4800/9600/19.2k/38.4k/57.6k/76.8k/115.2k bps
Set with parameter
Communication
method
Half-duplex communication method
Synchronous method
Asynchronous method
Transmission code
Binary
Transmission method
Transmission from the lower bit (LSB first)
Applicable
RS-485
Data bit length
8 bits
Parity
None/Even/Odd
Set with parameter
Stop bit length
1 bit/2 bits
Set with parameter
Start mode
Half side start method by command from Host-Side
Commands
Waiting time
Silent interval + 0 to 1000 (ms)
Set with parameter
Connection type
1: N (N = Max. 247)
(Up to 32 units can be connected without repeaters
(including master))
Set with parameter
Error checking
Overrun/ Framing/ CRC-16/ Longitudinal parity
Code
Item
Description
Data
[A001]
Frequency source
selection
Set for Modbus communication
03
[A002]
RUN command
input source
selection
Set for Modbus communication
03
[C021]
[C022]
[C026]
Output terminal
function
Communication line disconnection [NDc]:
This signal turns ON when a communication error occurs.
32
[C071]
RS485
communication
baud rate
selection
Set the baud rate from the following.
03(2400bps)/04(4800bps)/05(9600bps)/06(19.2kbps)/0
7(38.4kbps)/08(57.6kbps)/09(76.8kbps)/10(115.2kbps)
03 to 10
[C072]
RS485
communication
node address
Assign the node address of the inverter.
1 to 247
[C074]
RS485
communication
parity selection
No parity
00
Even parity
01
Odd parity
02
[C075]
RS485
communication
stop bit selection
1 bit
01
2 bits
02
A
Q
!