LabVIEW drivers - Eurotherm Mini8 controller with OPC
It's easy to setup the connection between LabVIEW and your Eurotherm Mini8 control unit. With the OPC server running and the provided demonstration program it should be easy to create some working program. morechemistry.com shows an example of a setup with 2 temperature controllers and 2 temperature indicators inside the control unit.
Communication with a Eurotherm control unit works like this:
- run the OPC server and attach it to the Mini8 controller
- both for all read channels and all write channel create an OPC reference
- for all read channels read the process value
- for all write channels write the setpoint if it has changed
- at fixed time intervals repeat the previous 2 steps until some condition is met e.g. the STOP button has been pressed
- for all channels remove/close the OPC reference (in reverse order?)
- stop/close the OPC server
This file contains:
- eurotherm opc - read.vi
This vi (functional global) opens the OPC connection, executes read actions and closes the connection.
- eurotherm opc - write.vi
This vi (functional global) opens the OPC connection, executes write actions and closes the connection.
- eurotherm opc - sample.vi
This vi shows how to use the driver vis with a Mini8 control unit and a mix of controllers and indicators.
- eurotherm opc - sample globals.vi
This vi contains the global constants required by the sample program.
All these vis have been made with LabVIEW 8.5.1.
The control unit in the example is connected to COM1 at a baudrate of 19200.
The OPC server that comes as part of the iTools software is, by default, a demonstration program. It is fully functional but it terminates the OPC connection after exactly 30 minutes. Without any precautions this disconnection will completely distort the execution of LabVIEW.
Bart Boshuizen, 2010/04/07