Multifunction DAQ

Showing results for 
Search instead for 
Did you mean: 

Connecting a 4-20mA loop powered sensor to USB-6255

Go to solution

JoeKellyATI wrote:

Do I have the sensor wired up backwards to the diode?

Yes you do.  The current needs to flow out of the power supply, into the sensor, out of the sensor and then through the diode to the power supply return.  With your diagram, to current flows counter clockwise.  So to have current flow through the diode, it needs to be in the same direction as the diode is pointing (look at the diode as an arrow).  Otherwise, it looks like that optocoupler will work.

There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
"Not that we are sufficient in ourselves to claim anything as coming from us, but our sufficiency is from God" - 2 Corinthians 3:5
Message 11 of 13



Here is an updated schematic for future people who stumble upon this thread:

Pressure Switch.png

I'll purchase that optocoupler and call it good.


Thanks everyone!

0 Kudos
Message 12 of 13

Here's the final (working) schematic for the pressure switch:Pressure Switch Schematic_schem.pngThanks for all the help!



0 Kudos
Message 13 of 13