ScadaMobile supports any modern Omron controller. For small size (and price) you can look into the Omron CP1 family. Most of them can be fitted with an Ethernet Option Board, which will work just fine with ScadaMobile. Unfortunately the Ethernet Board can not be pugged in the very entry level CPUs, but still you may find a combination that suits your needs for small size at a reasonable price. These Omron controllers are similar in size and features to the Allen Bradley Micrologix series, also supported by ScadaMobile. Depending on your particular dealer or Country, Omron controllers tend to be somewhat cheaper than the equivalent Allen Bradley controllers, and they are one of the most (if not the most) reliable and trouble free controllers in the market.