In my setup, the 3-wire hall-effect flow sensor with the signal wire is connected in series to a pulse counter. The power wires (pos and neg) for flow sensor are connected normally to 5vdc. To feed its signal into a wireless Monnit pulse counter and have it to show up on their cloud server as data, the Monnit specs say the black wire on a single-input or 4-input multi-pulse counter is used as ground or common, but that is for 2-wire flow sensors and no one has any advice to give me when going off the beaten path into 3-wire flow sensors.
For my hall-effect flow sensor to output pulses, I have to use the sensor’s black wire to create the data stream by plugging it into an Arduino UNO board(digital pin 2). The pulse transmitter/sensor get its other (red)wire attached to signal output of 3-wire flow sensor.
I’m able to get pulse data on the iMonnit cloud server with this 3-wire flow sensor:
Multi Pulse Counter – 75940
10/6/2017 1:42 AM
Pulse count was 105. The other three zeros before it were unused from the 3 unused wires as you can use a total of four counters in this device. Check-ins are at default 2-hr. intervals to conserve battery life. Also the 4-input pulse sensor only outputs raw pulse data, you can’t scale the pulses into gallons as you can with their single-input pulse sensors. But either way, you can still use Monnit notifications for SMS or email alerts if numbers get too high or drop to zero for a set interval of time. The latter would be helpful for an irrigation system with a dead valve or cut solenoid wire, as the irrigation controller would function independently and not detect that problem in the field.
Now I just have to figure out how to wire in multiple flow sensors with the multi-input counter without using multiple Arduino Uno boards.