Communications D - 2Using Modbus CommunicationSerial communication can be performed with Program Logic Controllers (PLCs) or similar master devices using the Modbusprotocol. Modbus Communication ConfigurationModbus communication is configured using 1 master (PLC) and a maximum of 31 slaves. Serial communication betweenmaster and slave is normally initiated by the master and responded to by the slaves.The master performs serial communication with one slave at a time. Consequently, the slave address of each slave must beinitially set, so that the master can perform serial communication using that address. Slaves receiving commands from themaster perform the specified functions, and send a response back to the master.Fig D.1 Example of Connections between Master and Drive Communication SpecificationsThe Modbus communication specifications are shown below:Table D.1 Modbus Communication SpecificationsItem SpecificationsInterface RS-422, RS-485Communications Cycle Asynchronous (Start-stop synchronization)Communications ParametersBaud rate: Select from 1200, 2400, 4800, 9600, and 19200 bps.Data length: 8 bits fixedParity: Select from even, odd, or none.Stop bits: 1 bit selectedCommunications Protocol Modbus RTUNumber of Connectable Units 31 units maximumMasterF7 F7 F7Slaves
