Ready I/O Shield

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Joined:Wed Nov 02, 2011 11:47 am
Ready I/O Shield

Post by sawtellda » Wed Nov 02, 2011 12:10 pm

Something that surprised me when looking through the shield list was how few boards there were with basic digital I/O. I'd like to see a digital shield or shields with some opto-isolated inputs and relay or external voltage transistor outputs. Pin assignment via jumpers or solder links. Say 4 in 4 out with screw terminals suitable for interfacing with 12V and 24V DC controls.

I wanted to use an Arduino for a quick repair job and ended up using a cheap PLC which was overkill but quicker.
the circuitry is trivial though I am sure beginners and those interfacing home automation would appreciate a quick solution. This plus DIN rail mounts like those from Rugged Circuits turn an Eleven or an Ether-Ten into a ready to go instant controller.

Mild Lee Interested
Joined:Fri Feb 03, 2012 7:46 am

Re: Ready I/O Shield

Post by Mild Lee Interested » Fri Feb 03, 2012 8:27 am

I agree! I've built a couple of versions of this sort of thing on proto boards using optos like 4N33 or LTV8141 for inputs and photoMOSFETs like ASR-1228 for outputs. These MOSFETs can switch 200mA - enough to run a small relay and certainly enough for a PLC input.
I have also included a monolithic switching regulator (R-78B5.0-1.0 Pricy, but very small) to give me my 5V from 24V.
I use these shields as cheap industrial commissioning and fault finding tools. You can do a lot of things with just a couple of inputs, a couple of outputs and a bit of logic in between. It would be great to have one "ready made" as mine look a bit of a mess on protoshields!

My wish list would be:

-Between 2 and 4 opto isolated inputs accepting 24Vdc .
- at least 2 opto isolated outputs capable of 200mA at 24Vdc with PTC or polyfuse protection.
- all optos and MOSFETS DIP packaged and socket mounted (for when I inevitably burn out a channel!)
-5V Arduino supply from 24Vdc input - with option of disconnecting (for use with USB)
-Blinkin-lights to show I/O states.
- pluggable screw terminals!
- A general purpose push button or 2.
- A general purpose LED or 2.
- low profile so another shield can sit on top.

I have got ALMOST all this onto a proto shield - so it shouldn't be to hard to do a proper one!
24V IO protoboard

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