Just make sure that the 2604 is set-up and working from the Eurotherm Modbus server. You can then create controls and indicators in Labview and connect them to items on the 2604 using Datasocket connections. I have an application that has been running this way for several years without any problems. By the way, custom instruments can be created in the modbus server. This is one way to communicate with almost any instrument to OPC. Create a virtual instrument in the Eurotherm modbus server, create a VI that communicates with the actual instrument, then link the two using Datasocket. You now have an instrument that can be accessed by any OPC client.