I am devising a network monitoring and controlling connection to maintain a decent environment for for my Guruplug network routers. I will be enclosing all three guruplugs in a single case. The existing GP's cases are crumbling so a radical solution is needed. As we know, Guruplugs run hot and cooling is needed. I will be using an old PC PSU to provide 5V (and 12V for fans). I will be monitoring the temperature using DS18B20's (or are the DS 18S20's I can never remember) attached à la Confusticated's sticking to the CPU as described elsewhere. There will be a Raspberry Pi equipped with a Piface module and a DS2482 I2C to 1-wire reading three (possibly four) DS18B20's with OWFS and passing the data back to the central, duplicated automation controllers, which are also Rpi's. Thats the easy bit and I already have temperature monitoring (using rrdtool) examples in service.
The other half of the project is the Piface equipped RPi in the network router box which receives commands from the automation servers over the network and turns on the fans as required. For me it is no problem controlling the fans that will be attached to the Piface's relays, nor the software mechanics of getting data received from the automation servers and decoding it. I have already done this with a couple of ethernet relay boards using a very crude modified telnet protocol (not my devising I might add). Of course you may be thinking that the RPi in the router case could perform control autonomously but thats not the way I want to do it.
At present, my mind is blank about what protocol I could use across the LAN for control. I could use an adapted telnet/ssh message protocol, devise my own protocol, use some sort of home automation protocol for message passing (e.g. MODbus, X10).
Help me clear this mental block please! 