Data Mapping via Internal Polled Vs External Polled..?

[Talha.Ejaz]

Hello Support Team ,

First of all I would like to Thank the whole team who is always providing us continuous support in solving our issues. I am student of MSC Electrical Engineering and currently writing my Masters Thesis in a company where i have to implement OPC UA protocol for the communication between different systems, i m new to OPC UA and a month ago we decided to use Unified Automation .Net SDK for building a server.

I have a lot of confusion regarding the Data mapping . I have read all the Topics and also thoroughly saw the tutorial Examples till Lesson 3 , but still i am unable to figure out whether in my Application i have to use simple LinkModelToNode or i have to use Extrernal Polled and overriding Read and Write Method. That's why i would like to explain the scenario of my Application so that you guys can give some Tips regarding data Mapping.

Here in this company , i have to extract the data from PLC Simulation which is the device. but a separate PLC Gateway in C# has already been developed which is just making connection to the PLC Simulation(Device) , doing Polling to receive the data from PLC Simulation and converting the data to normal string,int and Double variables. I have used UaModeller to create the OPC UA Server and then i simply integrated the OPC UA server in that PLC Gateway C# program.The data changes in PLC gateway are event based.

Now in the single C# Program i have PLC gateway and OPC UA server as well ,and i have to map the variables of PLC Gateway to the address Space of OPC UA server. As data polling is already being Done in PLC Gateway , i guess that i dont require the External polled mechanism here or may be i am wrong and it is still the case that PLC Gateway is External Source,My opinion is that, PLC Gateway and OPC UA server are in the same program and i think that may be LinkModelToNode should be fine here and i can just assign the variables in gateway to the Instance of ModelClass in Node Manager. but i am not sure which mechanism suits my application . Can anyone please help me in this Regard , i will be very Thankful.

Regards ,

Talha