Is it possible to build a PLC with arduino / other microcontrollers?(i just heard someone discussing such a project with a pic controller.) How would one proceed?
I think it should be possible. More like putting a suitable firmware and designing appropriate hardware..or am i taking it too easy?
Well... it depends on what aspects of a PLC you except to be able to replicate? If you are just talking about a ladder logic based software, it is possible. I toyed with the idea a little bit, as a method to introduce old electricians to embedded development. Didn't get past a design stage though, as it was easier and more functional to teach them a c like syntax then to accommodate a dying language for them
You could check out the "CUBLOC" from comfile technology. It has ladder logic + BASIC programming, though no C. Price is quite low, but be aware that support seems to be non-existent.
Arduino pretty much is a PLC running C at a fraction of the cost of a commercial unit with similar features.
Check out the I/O specs on the Mega and compare it against a name brand PLC.
PLC's tend to be hardened for industrial service and feature things like terminal blocks, optical isolation and can usually handle higher switch loads i.e. 24VDC relay operation.
You can do all the same things as a PLC but you probably wouldn't want to run mission critical applications with an Arduino. As a hobby device they're fantastic.
PLC's tend to be hardened for industrial service and feature things like terminal blocks, optical isolation and can usually handle higher switch loads i.e. 24VDC relay operation.
Which makes me think of: http://www.ruggedcircuits.com/