My former customer needed to talk to their PAC controllers via ethernet from Linux. We accomplished the task by connecting to a predefined controller port and reading / writing to it from the Linux PC. On the controller side we ran a couple of charts collecting and setting the required data. Basic client/server - read stuff, dump it into an array, ship it over when requested. It works reasonably well but I consider it somewhat clumsy. And we haven’t found any better way so far. We considered using the scratchpad for brief period of time but it became very clear that was not a viable solution.
It appears that one ought to be able to write (any OS) native application able to connect to the controller via ethernet and get / set any data in memory with MMP (http://www.opto22.com/documents/1465_OptoMMP_Protocol_Guide.pdf).
So, 2 questions:
- Is there a better way than what we did? Linux Opto OPC server perhaps? Other existing Linux commercial software?
- Before I dig any deeper - I am curious whether there are any Linux / Unix users interested in having a native application capable of talking to PACs.