Individual Functions; Using Modbus Communications - YASKAWA G7 Series Technical Manual

Individual Functions

This section explains the individual functions used in special applications.

Using MODBUS Communications

You can perform serial communications with MEMOCON-series Programmable Controllers (PLCs) or simi-
lar devices using the MODBUS protocol.
MODBUS Communications Configuration
MODBUS communications are configured using 1 master (PLC) and a maximum of 31 slaves. Serial commu-
nications between master and slave are normally started by the master, and the slave responds.
The master performs signal communications with one slave at a time. Consequently, you must set the address
of each slave beforehand, so the master can perform signal communications using that address. Slaves receiv-
ing commands from the master perform the specified function, and send a response to the master.
Communications Specifications
The MODBUS communications specifications are shown in the following table.
Interface
Communications Cycle
Communications Parameters
Communications Protocol
Number of Connectable Units
-84
6
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MEMOCON-series PLC
RS-485 connections
example
Fig 6.54 Example of Connections between PLC and Drive
Item
RS-422, RS-485
Asynchronous (Start-stop synchronization)
Baud rate:
Data length:
Parity:
Stop bits:
MODBUS (RTU mode only)
31 units max. (when using RS-485)
Drive Drive
Specifications
Select from 1,200, 2,400, 4,800, 9,600, and 19,200 bps.
8 bits fixed
Select from even, odd, or none.
1 bit fixed
Drive