MarkT:
retrolefty:
The polarity symbols you have drawn for the round temp and RH are backwards.Ah, that's not actually true, since the sensor is drawn as a current-source, and the signs represent current
measurement direction, not voltage. Usually the signs aren't written as the arrow serves to indicate
polarity.
I'm speaking from a real word situation where all such '2-wire 4-20ma transmitters' have just two terminals labeled + and -. The + must wire to the positive loop voltage source and the - must wire to the series 150 250 ohm resistor, which then wires to the negative loop voltage terminal.
Lefty