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(1) Communication specifications
⋅ The communication specifications are given below.
Item
Communication protocol
Conforming standard
Number of inverters connected
Communication speed
Control protocol
Communication method
Character system
Start bit
Stop bit length
Communication
specifications
Parity check
Error check
Terminator
Waiting time setting
(2) Outline
The Modbus protocol is the communication protocol developed by Modicon for programmable controller.
The Modbus protocol performs serial communication between the master and slave using the dedicated message
frame. The dedicated message frame has the functions that can perform data read and write. Using the functions,
you can read and write the parameter values from the inverter, write the input command of the inverter, and check
the operating status. In this product, the inverter data are classified in the holding register area (register addresses
40001 to 49999). By accessing the assigned holding register address, the master can communicate with the inverter
which is a slave.
REMARKS
There are two different serial transmission modes: ASCII (American Standard Code for Information Interchange) mode and RTU
(Remote Terminal Unit) mode. This product supports only the RTU mode in which 1-byte (8-bit) data is transmitted as-is.
Only the communication protocol is defined by the Modbus protocol, and the physical layer is not stipulated.
Modbus-RTU protocol
EIA-485 (RS-485)
1: N (maximum 32 units), setting is 0 to 247 stations
Can be selected from 300, 600, 1200, 2400, 4800, 9600, 19200 and 38400bps
Asynchronous system
Half-duplex system
Binary(fixed to 8 bits)
Select from the following three types
⋅ No parity, stop bit length 2 bits
⋅ Odd parity, stop bit length 1 bit
⋅ Even parity, stop bit length 1 bit
CRC code check
Communication operation and setting
Description
1 bit
Not used
Not used
Related
Parameters
Pr. 549
⎯
Pr. 331
Pr. 332
⎯
⎯
⎯
⎯
Pr. 334
⎯
⎯
⎯
4
235
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