Module to read 24v inputs

NETMF & Gadgeteer
1

Hi ,

We need read 24v inputs from sensors.

We have seen this board in youtube, but, we cant found it.

https://www.youtube.com/watch?v=i3DInBXiNNk

Did you know where can we found some similar??.

In the past we was using optocouplers, to have differents input voltages, but, for now with 24v is enough.

thanks in advance.

raul

http://www.lafabricadesoftware.com
http://www.lavanderiacobos.com

2

That’s our old mate Justin’s modules, http://ingenuitymicro.com

He’ll pop along and let you know if they’re available for purchase

3

Thanks @ Brett,

I have seen your link, but they dont have products to purchase.

I have write an mail asking for it.

thanks for your attention,

raul

http://www.lafabricadesoftware.com
http://www.lavanderiacobos.com

4

@ rlcobos - I replied to your email this morning…

5

they do have stuff for sale. They just don’t have a web shopfront. And he’s pretty responsive, as you saw. And he’s an OK guy to boot, at least now he’s back in the UK and not sunning himself in NZ.

6

@ Brett - :smiley:

7

Hi,

I use 24V PLC signals in my project and use a simple resistor divider for it. For the connection I use the breakout board.

To get the right voltage, connect a 10k resistor from 24V signal to the port input and use a 2k2 resistor from the port input to ground.

Declare the port as input in code and voila, you have your 24V input…

Good luck!

Kind regards,
Aubert

8

@ A_Dupont - Even that your solution should generally work, I would never ever expose the CPU pins directly to an industrial environment.
You never know what might happen out there.
Also for your solution you have to connect the CPU Gnd with 24V Gnd, which not an good idea, specially if you do some analog stuff too.

9

After the resistor divider put a buffer amp-op (voltage follower), this way you isolate high/low circuit impedances and protect your MCU input. Check LM358 or similar.

10

I won’t use a voltage follower in this kind of appplications, usually 24VDC is industrial equipment that already have a low output impedance and the resistor divider have a high impedance input if resistors have high values >10K. Instead I would use a TVS diode to eliminate transiant voltage.