I am in the "conceptual" phase for a project and I am trying to figure out which way to go as far as controllers. I have 20+ years in Industrial PLC (Allen Bradley, Siemens, Direct Logic) programming but almost none in embedded microcontroller programming. I know exactly what I want to do and how I would do it in a PLC but how to accomplish the tasks in a microcontroller is something for another post. That said, PLC's use some sort of microcontroller... so it can be done
I have no qualms with using multiple controllers. For instance, one for data handling and one for control. How to do that is another matter but I'm not at that point yet. I would not want to split IO groups. For instance, 4 analogs on one controller and 4 on another.
The project has the following requirements-
8- scaleable analog optically isolated inputs (I can get by on 4 for this particular project)
4 - scaleable analog optically isolated outputs (I can get by on 0 for this particular project)
16 - Digital inputs (I can get by on 12 for this particular project)
8 - Digital outputs (Technically I only need 1 if I can use a serial display for textual alarm display)
Project wishes (these would make the project more attractive)
(1) Serial connectivity for current data retrieval and some configuration (like scaling). This would be RS232 or RS485 using the Modbus (slave) protocol or Ethernet using the Modbus TCP protocol.
(2) Bluetooth connectivity (see item 1)
(3) 32 bit analog data. Even 16 bit would be better than 8 bit. 12 works too.