I am working on a project to continuously measure the rpm of an engine and a bladeshaft of a a flat saw using hall sensors and magnets.
I have solved how to do this in theory but when setting it up the program is not able to count the pulses correctly. When measuring pulses the signal never goes down and the rpm measured is the highest possible. I have tried to define a pulse in two different ways. First by measuring when the voltage goes below 0 and second by measuring when the voltage is between a certain interval. I am using a pull down resistor but it still isn't working.
I have considered using the counter but since i only have one counter that is not an option.
I am using a CDAQ-chassi with the following modules:
NI 9207 - The one I currently use
NI 9401 - The one with a counter
Hi, what do you mean the signal "never goes down" ? What speeds are you expecting to measure (e.g. 100 samples/second etc)? What cDAQ chassis are you using? If you slow the bladeshaft down does it still see the issues? Are you using 1 sensor on one bladeshaft?
I think, first thing you have to know the pulse width, your sample rate is 10KS/s. that is 0.1ms get one sample.
If the pulse width is 1ms, so you will get 10 high signal.
The programming have to count the pulse up and down, then could say add one pulse to the counter.
You try my way, see it work?