The Yottacontrol's A-1xxx series is an interesting solution for remote i/o having a mix of channela of different types: analog and discrete inputs, outputs, temperature inputs and so on. For some small object, e.g. a greenhouse, only one module could be a total economy solution for sensor reading and load control.
The modules suppost Modbus RTU/ASCII protocols.
In the configuration utility there is a memory map for the I/O channels. Modules have 2 modes of operation - 'config' and 'normal', chosen with the Init/Normal switch: