Myio Goals
Change of plan See:This Update
In essence I'm re-inventing the wheel, but then that's fine as I'm doing this for the challenge, and because I can.
A lot of the 'hobby' level process control / automation systems I found on the web lacked fundamental integrity in their designs, and did not seem to be very 'robust'. I'm not saying I'll create anything significantly better, but I'll have a bit of fun trying, and maybe give some other folks a starting point for their own project.
What I want to build is a fully functional virtual PLC, and SCADA/HMI for Linux, along with my own modbus RTU design. The 'feature' list is below, and the 'status' is there as well. As I achieve the goals, or fail miserably I'll update this page. :-).
At this stage I'm not committing to releasing the code for the RTU's at all, but I am considering releasing the designs and code under the GPL. I think I'll wait and see if there is any interest in it first!
- Virtual PLC engine for Linux written in 'C'
- Simple to understand gcc code, not c++ weirdness. :-)
- Supporting up to the full 127 devices, with up to 2048 inputs/outputs
- ability to add non modbus inputs such as software triggers/events.
- keep an eye on complexity of design for possible move to a PIC18F based PLC design in the future using the same HMI/Scada engine.
- HMI / Scada system using LAMP stack (Linux/Apache/Mysql/PHP)
- web based GUI for config of RTU's and logic of PLC
- input simulation / override for testing of logic
- trending / history of points and aggregate data.
- modbus compatible RTU's using cheap PIC 16F* processors supporting:
- two-wire RS485 comms
- isolated digital input and output
- Isolated 4-20ma / 0-20ma / 0-1v / 0-10v 12bit A/D
- timer-event digital outputs (pulse high/low for XXms)
- interval/event counter inputs
- Fully modbus compliant (See near the bottom of News from 3rd Feb 08)