SiggyTheViking

It seems that all the discrete outs are energized at boot up. Is there any way to avoid (or configure) this? Siggy

So, nerd that I am, the itch I want to scratch is to build out a control system for my ranch. The very first step is to put my N+ in my well house and monitor pump starts and stops, so that if I have a leak I can notice before I get an extra $500 on my electric bill. Pump starts, 240V relay closes, DI0 is closed to ground, N+ does an HTTP post to my web server, which writes the status ("on") and the timestamp to the database. When the relay opens (pump goes off), N+ posts status "off". So far, so good, and it works.

My real question, though, is what should my architecture be going forward. The next thing I want to add is an output from the N+ that closes a relay to open my gate, so we don't have to march down the hill with a clicker in hand when company arrives.

This, of course, is the beginning of a SCADA system. I have a controller in the field that does what it is programmed to do, if anybody is watching or not. It sends messages when interesting things happen, it sends its state when asked, and it does things when told by the HMI (the politically correct Human Machine Interface). All this can be done over HTTP, but it seems like a lot of overhead for a pretty clearly defined domain. I am happy enough writing the HMI in a web page, as I am reasonably fluent in that sort of thing, and it allows such goodness as my lovely daughter opening the gate with her iPhone, but I'm thinking that I don't want the N+ getting these web requests directly. If I implement the I/O to and from the N+ as a daemon process on the server, it also simplifies things like scripting cron jobs to turn on the sprinklers.

So, with that sort of verbose bit of background, I think I need a socket server at each end, and a simple communication protocol. Any suggestions as to what I should do to whip this up, or even better, what I should rip off? I have started poking around the net to see if there is a sensible implementation of Modbus for .NET that will fit, but at this point I can't tell if it would be a gain in efficiency or space.

Make sense?

Siggy