All manufacturers of PLC's have good points, however AB & Siemens seem to be a bit expensive especially the programming software. so the choice is yours, just think about local suppliers and stocks (I'm sure you will not want to keep all cards in stores due to costs). RS components are a good source for some spares on small PLC's and they usually carry reasonable stocks and available next day. One thing you might like to look at on the Scada side is Movicon, You can get trial software that is fully functional for 2 hours at a time. contains many I/O drivers as standard (no extra cost) is easy to use and is priced on I/O count which is upgradable by stages. It has fantastic and easy to use functions, scripts, events, database logging, alarms, large array of usable symbols, graphs etc. If you need to keep costs down use SQL Server Express, however you are limited to 4gb, but ask your IT Dept. they may have SQL licences already.