acquring Digital Input NI DAQ 9401 chasis NI 9178

[vnarang]

Hi Guys,

I need your help badly.I have a flow meter which generates pulses(digital waveform),I want to measure the freuency of these pulses to get flow.

Flow meter range is 0.2-18 gpm,it generates 330 pulses per gallon.

I am using Ni 9401 to acquire this data.In Signa express i am using edge counting to measure the data.I browse may website and every where it says its pretty simple but my counter is always reading  zero,even though I increased my flow to maximum.

Please suggest me something.

I talked to NI application engineer on phone,he told me I might have problem with ground,I am not usre if it is going to solve my problem.

My flow meter has 3 wires,flow meters needs DC voltage of 5 volt,so two wires fro DC and the third wire is for signal,I have connected this wire to NI 9401 at pin 16 whose counter is zero.I have no idea if grounding is the only issue as of whcich my couner is not reading above zero.my flow meter has only one signal wire ,and if i want to correct my grounding how can i do that.

Please advise me somthing

Thanks and regards

Vikas

[AnalogKid2DigitalMan]

Vikas:

Please keep to your original post here, where you were getting answers. http://forums.ni.com/t5/LabVIEW/flow-measurment-using-labview/m-p/1614608#M584855

Yes, you need to connect the (-) of the 5V supply to one of the COM pins on the 9401 as I suggested in your original thread.

-AK2DM