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Communication operation and setting
4
PARAMETERS
(1) Communication specifications
⋅ The communication specifications are given below.
(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.
Item Description
Related
Parameters
Communication protocol Modbus-RTU protocol Pr. 549
Conforming standard EIA-485 (RS-485)
⎯
Number of inverters connected 1: N (maximum 32 units), setting is 0 to 247 stations Pr. 331
Communication speed Can be selected from 300, 600, 1200, 2400, 4800, 9600, 19200 and 38400bps Pr. 332
Control protocol Asynchronous system ⎯
Communication method Half-duplex system ⎯
Communication
specifications
Character system Binary(fixed to 8 bits) ⎯
Start bit 1bit ⎯
Stop bit length
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
Pr. 334
Parity check
Error check CRC code check ⎯
Terminator Not used ⎯
Waiting time setting Not used ⎯
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.