Posted 20 Oct 2017 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 Share this post Link to post Share on other sites
Posted 20 Oct 2017 Update: The sensor I am using is an IP810 hall-effect sensor current sinking pulse. Share this post Link to post Share on other sites
Posted 20 Oct 2017 Most paddle wheels end up needing some pull up resistors on them. Look in the details of the wiring diagram and see if it doesn't say anything about that. Share this post Link to post Share on other sites
Posted 20 Oct 2017 Update: The world makes sense again. Being that this is a sinking device, I needed to measure across power and signal instead of signal and ground. Now, I need to figure out how to wire this up to my plc...maybe I can use an opto-isolator to convert to sourcing? I could maybe rewire the group of inputs as sinking, I will see. Thanks, neech Share this post Link to post Share on other sites
