IGS-NT Communication Guide
129
9 Modbus Connection
Modbus protocol was implemented into the controllers to enable the customer to design its own supervision
software.
9.1 Modbus Step by Step 129
9.2 Important setpointsin the controller 129
9.2.1 Modbus communication via RS232 – single controller 130
9.2.2 Modbus communication viaRS485 130
9.2.3 Modbus communication via RS485 – multiple controllers 131
9.2.4 Modbus communicationviaI-LB+ 131
9.2.5 Modbus communicationvia IB-NT 132
9.3 Modbus Protocol Description 132
9.3.1 Modbus TCP 132
9.3.2 Modbus RTU 135
9.3.3 Alarm list reading 139
9.3.4 History reading 143
9.4 Check field calculation 143
9.5 How get numbers of Modbus communication objects 143
9.6 User Modbus 144
9.1 Modbus Step by Step
9.2 Important setpoints
in the controller
There are three possibilities of Modbus connection to single or multiple controllers: Via RS232 or RS485, IG/IS-
NT-BB controllers is possible connect via Ethernet port (TCP/IP ModBus).