The attached code (an exported Structured Text Section) will demonstrate sending a TCP/Modbus read register request from a PLC to a modbus device.
The code is extensively commented and can easily be modified to send any supported modbus message. Simply open a Unity project and import the section.
It was created using Unity Pro ver 12.0 and an M580 PLC but should be able to be used with any version of unity and any PLC that supports the
DATA_EXCH fb.

Released for:Schneider Electric Canada