Yes, you can add something like 256 modules... more than 1,000 independently controlled outlets and hundreds of probes; so I don't think we'll ever "outgrow" it.

I like what you're doing, I just don't see how you can come close to the APEX system for the price. By the time you work out a web-server, remote monitoring & control, build relay modules to control things, etc.

They (Neptune Systems) claim that "galvanic isolation" of the various probe circuits is essential in order to get reliable, accurate readings, FWIW.

The APEX manual is here, maybe there are some ideas you can use: http://www.neptunesystems.com/wp-con...nce-Manual.pdf