Large Scale Control

If you wanted to control a very large number (100s) of solenoid switches from a PC how would you do it?

Similarly, how would you handle feedback from a very large number of sensors?

There are plenty of industrial control type interfaces on the market which would do the job. But they get rather large and often have a card in the PC coupled to an external box which has the high power switching stages and the terminals for connecting things.

But these days it is becoming common to distribute this sort of interface over a number of intelligent cards each with a microcontroller on it. For controlling an industrial machine I did a board that has 8 solenoid drivers on it, 2 high power stepper motor drivers and provision for monitoring current in each solenoid, temperature (if a small sensor is fitted) and an additional 16 channels of switch input and 16 channels of analog voltage input. This is done using a Rabbit 2000 processor and originally had a serial interface which has just been updated to USB. Eight such cards are used in each machine.

These sorts of things are available commercially, but they are not cheap.

You could build something similar using an Atmel mega-AVR, a Rabbit or an ARM based controller. I don’t think the PIC is gutsy enough for this sort of job.

Good luck!