I have a pressure sensor that has two wires, one + the other -. How would I connect this to the Monitor One I/O extender? The Monitor One datasheet shows connecting the 24V input power, ground, and 4-20ma input to the sensor (Block diagram - I/O Card) but my sensor only has two wires. I apologize for my ignorance. The schematic of the 4-20mA INPUT appears to be shunt. Am thinking that the - wire from the sensor would connect to the 4-20ma input and the + wire of the sensor would connect to 24volts but I don't want to destroy my Monitor One. Can someone help me?
What sensor do you have? Do you have a datasheet?
Sone sensors will pull 4mA to power itself, and the rest will be the signal feedback.
This is a Brand ZGCj Model Cj-YBT sensor. Hopefully the image of the wiring diagram is here. This is my first post and just getting started with Particle devices.
I've been using it with a R Click 4-20ma module that handles the conversion and has an SPI interface.
I connected the - line to the 4-20ma input on the expansion board and + line to the 24V input and it works great. Sure would be nice to have a 3.3v to 24v on the expansion board to use with 4-20ma and 0-10V sensors as I'm looking at solar panel input which won't always be available. Maybe a 100ma max and an enable so that it could be disabled to save power when not taking readings.
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That's great news!
You can easily add your own custom expansion board to accomplish this - though 24V boost converters are not as easy to come by as 12V.
I've used these before in a pinch: https://a.co/d/gzo6kDM
No Enable pin, but a MosFET could do that for you. Otherwise a boost converter from Ti or Renesas would do the trick.
Chris, Thanks for the response. I'll start with the "in a pinch" modules. For the particular sensor I'm testing with now 12V would work.
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