Near Intersection of I-35 & I-90 Southern Mn. | Possibly the third wire which should provide power to the circuit board inside the flow meter is partially broken. A meter might still show continuity on that wire if a few strands are still connected since the meter does not put much electrical load on a wire when testing it. Without good power, the circuitry will not operate reliably
Here's how the flowmeter works. Three pins and wires are involved. The pins at 2 and 10 O' clock provide power and ground to the internal circuit board. Then as the internal turbine spins due to product flow, the magnets on the turbine pass by a Hall effect sensor. This sensor will cause the signal pin to be shorted to ground temporarily and then released when the opposite magnet passes by. When the signal wire is released from ground it will return to the voltage of the power pin due to a pull-up resistor. This creates a pulse due to each magnet reversal.
The electronics in the controller literally counts these pulses for a period of time and converts the pulses/min into familiar units such as gallons/minute by dividing by the flow meter calibration number. This is the number you see when you view the Vol/min. It is used with the Area/hr value to calculate the applied rate/acre.
When shorting the signal pin at 6 O' clock to ground you are creating a pulse which should and apparently is showing on the display. However in actual use, the circuitry in the flow meter needs to have power to to do this. Thus a weak power connection might explain your situation.
It appears that the only thing you haven't swapped is the cable between the controller and the flow meter. |
Raven flow meter problem
