I have a "paddle wheel" style flow meter that I am trying to wire to my Micrologix 1400. It is a three wire device and there is a tag on it that says it can run at 6-36VDC. So, naturally, I thought to wire this to one of the HSC inputs of the Micrologix directly.
I hooked the ( + ) on the meter to 24V, ( - ) on the meter to common, signal to the oscilloscope, and ground on the scope went to common. I see a small 60Hz sine wave @ like 5mv when the wheel is not turning. When the wheel is turning I get a small square wave but in the same mV range. It is not a nice smooth square wave either its all jumbled up with the 60Hz sine wave.
I hooked this thing up to a transmitter and scoped the signal and ( - ) in parallel with the wheel - I get a nice smooth square wave signal when the wheel turns. It is only at 4.5V though.
My questions are? Why does't the paddle wheel give me what I am expecting directly? Also, what is the voltage range on the pulse that a micrologix will see? I am assuming that it will not count a wave with a 4.8V amplitude....
Thanks for your help in advanced!
neech