Reed switch with Rio

I have a float switch (which is actually a type of reed switch) shown below that says on the label:

240 VAC, 0.14A
120 VAC, 0.28A
120 VDC, 0.07A
24 VDC, 0.28A

and there are 2 wires to connect. I cannot locate any wiring instructions for this switch, but my non-electrical mind says something like the SNAP ICD5-SW, which “supplies 15 volts of power to an external dry contact switch and senses switch closure” would work. I’ve got a newly freed up Rio to use and am wondering if I supply this switch with 24V (from the Rio or elsewhere), then can I use the Rio to detect the switch closure? FWIW, I have a 24VDC power supply powering the Rio. If the answer is yes, which Input on the Rio would I use?

It is even easier than that!

The RIO has a switch input type… so it will provide the ~10 vDC required to detect the switch status.
Here are the specs.

Here is the wiring diagram.

Just select Switch input as the I/O type.

Its very simple.
You just wire the two wires from the switch to the channel input terminals on the RIO, select the type, hit save and you are up and running.

BTW, all these screen shots came from a RIO.
Just dig your way into the I/O Reference menu from here;

Lets know how you go.
(Also, lets know if you need a hand moving the data out of the RIO).

Perfect, thank you. I will hook this all up tomorrow and report back. I have a good comfort level getting the data in & out using Node-RED. This particular application is a heated tank with two solenoids feeding fluids into the tank, two float switches and two Type K thermocouples. I think I can do it all with one Rio.

1 Like

The instructions above were perfect! The reed switch functions exactly as one would expect.

Next item sitting here is a 24v dc solenoid valve that has 3 wires. No wiring diagram online that I can find, but a few videos that basically say the 2 red wires have no polarity.

Which output to select on the Rio and how to hook up this solenoid valve? I believe it’s Voltage Output and (assuming channel 4), connect the 2 red wires to 13 & 14…but where does the ground go?).

You would use one of the relay outputs or DC sinking outputs along with a 24VDC power supply in series (1A current limiting or include an inline fuse). Since this is a solenoid (inductive), you will need a diode across the solenoid in the reverse direction to suppress transients when the coil is de-energized.


Here is a drawing with the diode drawn in. A 1N4001 diode should work fine along with many others.

In short, listen to @philip
That said, have a part number for the solenoid?
The fact that its three wire has me intrigued.
But yeah, I would wire it one wire to positive, one wire to the RIO output and the third wire to the RIO output ground.

The third wire is a grounding wire that should be connected to the equipment grounding conductor. Not to be confused with Beno’s use of the word ground. The two reds are what you would use in the above circuit.

Some old photocopied instructions:

Uh, rushing while having dinner… my bad, I totally missed the link to the device…
Yeah, its not an active device at all (as I was thinking it might have been).
Like I said, listen to @philip

EDIT. Also please use a flyback diode.

Thanks guys. I will pick up a 1A fuse and flyback diode to do this right.

Just to clarify, my options on the Rio to use this solenoid is EITHER one of the relay outputs OR a DC sinking output (along with a 24VDC power supply). I can see the Form C Relay option in channel 8 & 9, but where is the DC sinking output choice (in the other channels). This one?

Im currently at home and don’t have a RIO here… I know, I know…
But, here are my notes on the digial output from a soon coming video on the RIO I/O.

Discrete DC Sinking output is when the RIO acts like an SSR, a solid state relay. It will turn on and off an externally supplied 5 to 30 volt DC source. The key to note in the specifications on this point type is the maximum continuous current of 1 amp. You should make sure you have external fusing or current limiting to ensure this is never exceeded. Also note that just like an SSR, there is a tiny amount of off-state leakage current.

Yes the 5-30 VDC Digital Output is the correct choice.

You can skip the fuse if using a current limiting power supply. Meanwell HDR-15-24 is cheap and meets the specs.

Got it. I probably will use the Form C relay since I have no other planned use for channels 8 or 9.

And finally, last in my box of unused electrical gadgets, I have this inductive proximity switch. Originally, I thought it would behave the same way as the reed (float) switch, but hooking it up in that way has not yielded any change in the state (I am expecting a state change when I pass something info front of the prox switch). Any thoughts on how to get this working with the Rio?

Uh, Um, 2 wire prox is going to be tricky…

Maybe that’s why it was in the unused box of electrical gadgets! (everyone has a junk drawer…this is a junk box)

If I managed to find a 3-wire prox switch, does that make things any easier for connecting to the Rio?

(BTW: also in the box was a Type K thermocouple and that is working perfectly in channel 3)

Yep, don’t know much about those - looks like it is designed to be in series with a DC load of 6-36VDC and allows current to flow when near an object, and just leaks a bit when open.

Spec sheet on that is hard to find, but it looks like it uses around 8mA (so the switch inputs on the RIO don’t provide enough excitation current). If you have a spare RIO analog output channel, you could set it up for 0-10VDC output and use that as a “power supply” (set to 10VDC output) for the proximity switch wired in series with a DC Input channel and see if it works.

Edit: DC Input channel won’t provide enough load to pass the current needed. You would need to try using a analog current input which should swallow the whole 20mA the 10V DC analog output can muster. If that works, you will read something like 8mA when the circuit is open and 20mA when the circuit is closed. If that works, then you can source yet another DC power supply (and fuse) for a proper power source.

Yes, three wire is a lot more doable. Just follow this guide.