I have to interface two digital comparators. These devices may be driven by a sort of musical chairs with files in folders its software watches. The nature of each device doesn’t lend itself to running an HMI of sorts along side the measuring software, so we are seeking an interfacing solution that requires no screen real estate. Concurrently in our approach, the data from the device is being displayed on an iPad mini. Hence, the “head”, insofar as the process is concerned, is that iPad mini.
Presently, I am considering deploying a trivial web service server to the device (available in the JDK since SE 1.6), and to query it using the web services interface. The service would do the musical chairs orchestration with the files, and reply, RPC style, with a measurement. I am confident this solution is workable, with remaining potential technical issues related to network connection persistence issues.
However, I would like to hear if there is a means of creating a headless ignition client that could watch an OPC tag (i.e. the request), perform the orchestration, and then update another tag (i.e. the response). It doesn’t seem like a trivial throw across home-plate to me, but perhaps I’m missing something in my understanding.