Modbus-Rtu; Communication Specifications And Setting Parameters - Hitachi WJ Series User Manual

Chapter 11

11.1 Modbus-RTU

11.1.1

Communication Specifications and Setting Parameters

 What are the specifications of Modbus communication function?
Q
 WJ-C1 inverters are equipped with RS-485 compliant Modbus-RTU port. They can communicate
A
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
Protocol
Baud rate
Communication
method
Synchronous method
Transmission code
Transmission method
Applicable
Data bit length
Parity
Stop bit length
Start mode
Waiting time
Connection type
Error checking
Code
Frequency source
[A001]
selection
RUN command
[A002] input source
selection
[C021]
Output terminal
[C022]
function
[C026]
RS485
communication
[C071]
baud rate
selection
RS485
[C072] communication
node address
RS485
[C074] communication
parity selection
RS485
[C075] communication
stop bit selection
Modbus-RTU (Slaves)
2400/4800/9600/19.2k/38.4k/57.6k/76.8k/115.2k bps
Half-duplex communication method
Asynchronous method
Binary
Transmission from the lower bit (LSB first)
RS-485
8 bits
None/Even/Odd
1 bit/2 bits
Half side start method by command from Host-Side
Commands
Silent interval + 0 to 1000 (ms)
1: N (N = Max. 247)
(Up to 32 units can be connected without repeaters
(including master))
Overrun/ Framing/ CRC-16/ Longitudinal parity
Item
Set for Modbus communication
Set for Modbus communication
Communication line disconnection [NDc]:
This signal turns ON when a communication error occurs.
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)
Assign the node address of the inverter.
No parity
Even parity
Odd parity
1 bit
2 bits
11-1-1
RS485 Communication
Specifications
Description
Remarks
Set with parameter
Set with parameter
Set with parameter
Set with parameter
Set with parameter
Data
03
03
32
03 to 10
1 to 247
00
01
02
01
02