flow measurment using labview

[Richard2950]

Have you put your signal on an oscilloscope to make sure that you have 5 Volt square pulses? That is the first thing to do. Make sure your signal is correct, then deal with getting the 9401 to count the edges, If those pulses are not there because of grounding problems or lack of pull-up then you will have no hope of counting edges with a 9401.

[vnarang]

Hi

I finally figureed it out now I am getting square wave in Labview signal express,But I am not able to undrstabd the signal,When I opted for measuring frequency,I got a graph with frequency on the Y axis and No of samples on the X axis and frequenxy was pretty much contant but yah it was perfect square wave.

Secondly when I used counting edges optiuon  counter is increasing .I hope this is how it is supposed to be.Please correct me and advised me if am wrong.

Now wtaht next I tried making some VI to measure the flow.But I am still having hard time.Please guys if you have Flow measuring VI please share.Is it possible to use counter and measure the flow on signal express.I will be working on my VI and will post for your help.

Thanks a lot!!!

Vikas

[vnarang]

Hi Guys

I am trying to measure the measure frequency,I believe i am doing rite.But when I am using counter input>> frequency option in labview signal express i am getting following graph(Please see the attached file)

I am confused with one thing on Y axis it says Voltage and its giving me in thousands,What does that mean?And Please guys if any of you know have flow meter VI please share.

Regards

Vikas

[vnarang]

I know I have to measure the either rising edges or falling edges over a fixed period of time and then divided the counter with time and in this way i can find pulses per sec and further do some calculation i can fin flow.But I dont knw how to make labview do it for me.

please suggest

[vnarang]

I HAVE ATTACHED vI WHICH i AM USING i AM USING COUNTER iNPUT>> EDGE COUNT,,i TRIED BOTH  1 SAMPLE ON DEMAND AND CONTINUOUS.eVERY TIME MY COUNTER IS GIVING ZERO VALUE.

pLEASE SEE THE ATTACHED FILE

[vnarang]

hi

[Joe_S]

Hi Vikas,

I see you currently have a phone support service request regarding the issue in this forum post.  It would be best for issues to be handled by either a forum post or a service request.  This is so that we can keep the information related to this issue in one location and resolve issues as quickly as possible.  For now, I recommend you continue to correspond with my colleague and you can work with him on a resolution to the issue.  Once a solution has been found, we can post the solution on here afterward for reference.  Thanks!

Regards,

Joe S.

[vnarang]

Hi

AS Discussed I tuk my flow meter signal to Osccope,DC power supply I am giving to the flow meter is 5 V,but in Osccop I am getting a square wwave of 1V.I tried to change the DC power supply to 12 V,still I am getting 1 V square output from the flow meter

Secondly when I am trying to acquire the same data in Labview.Frst I am not getting square wave and secondly,if I am using edge coount to count the rising edges my count increases at very fast rate.

Please advised me.

Regards

Vikas

[johnsold]

Do you have a pull up resistor connected to the output of your sensor? Or do you have the 4-20 mA version?  The data sheet says it produces a current sinking pulse.  For that type of sensor you generally need a resistor connected between the output and the positive power supply.  10000 ohms is probably a reasonable starting value.

Lynn

[Enzian]

Lynn has the right idea - connect a resistor to the output of your sensor. Let us know if this solves your problem.