Modbus Communications; Configure Master/Slave; Communication Specifications; Communication With The Plc - Omron Q2V Series Technical Manual

6.3 Modbus Communications

6.3 Modbus Communications
This section gives detailed information about the parameters, error codes and communication procedures for
Modbus communications.
◆

Configure Master/Slave

You can use the Modbus protocol for serial communication with programmable controllers (PLC).
The Modbus communication uses one master (PLC) and a maximum of 31 slave drives. Serial communications
usually starts with a signal from the master to the slave drives.
A slave drive that receives a command from the master does the specified function and then sends a response back
to the master. You must set the address number for each slave drive before you start signal communications to
make sure that the master uses the correct address numbers.
A - Master (PLC)
◆

Communication Specifications

Item
Interface
Synchronization method
Communication parameter
Communication protocol
Number of possible units to connect
◆

Communication with the PLC

This section gives information about the settings for the termination resistor and how to connect to Modbus
communications. Modbus communications uses an RS-485 interface (2-wire sequence).
■
Connect Communications Cable
Use this procedure to start communication between the PLC and drive.
190
B - Slave (drive)
Figure 6.1 PLC and Drive Connection Example
Table 6.2 Modbus Specifications
RS-485
Asynchronous (start-stop synchronization)
Communications speed:1.2, 2.4, 4.8, 9.6, 19.2, 38.4, 57.6, 76.8, 115.2 kbps
Data length: 8 bit (fixed)
Parity: even, odd, none
Stop bit 1 bit (fixed)
Modbus standard (RTU mode only)
Maximum: 31 units
Specification
SIEPCYEUOQ2V01A Q2V Technical Manual