I think you have to provide an external voltage source - the 4-20 mA circuits are sort of like the Sink-A and Sink-B circuits, they are just one end of something.
I connect my 4-20 mA pressure gauges to the same 24V source that supplies my power cape. Then the return path from the pressure gauge goes through the shunt resistor across the analog input. However, I’m not using this cape, I built my own shunt circuit on a protoboard. > On Feb 1, 2021, at 6:46 PM, Dwayne Zimmerman <[email protected]> wrote: > > So the pull down is to keep the voltage under 1.8 correct? My confusion is I > have one screw per input, 4-20mA is two wire where is the other half of the > circut? > > On Monday, February 1, 2021 at 6:40:01 PM UTC-5 RobertCNelson wrote: > On Mon, Feb 1, 2021 at 5:24 PM Dwayne Zimmerman <[email protected] > <applewebdata://F3584232-BCAC-41B2-985A-E8D4C88D94DE>> wrote: > > > > Thanks I have that. It doesn't detail the 4-20mA circut, unless I'm missing > > something. I'm trying to understand where power comes from and at what > > voltage. > > Each of those two connectors are connected to an adc pin. > > They both have a pull-down.. > > The ADC's can only take 1.8V, any more and they will fry.. > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ <https://rcn-ee.com/> > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/60ff116c-040f-47cd-a34f-58e726fb88d7n%40googlegroups.com > > <https://groups.google.com/d/msgid/beagleboard/60ff116c-040f-47cd-a34f-58e726fb88d7n%40googlegroups.com?utm_medium=email&utm_source=footer>. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/F0EF6982-7DA9-4F9E-B82E-0DFE21A64EC3%40gmail.com.
