Digital input to rpm

[ashnu]

Hello!

I am new to labview and I have a problem, please help me.... 

I have a Picoturn which measures RPM of the turbine. I have connected the digital output from picoturn to Port 0 and D.GND port in BNC 2110. The BNC is connected to M-series PXI-6251 card. From the DAQ assistant I am getting 1 and 0 when I run the turbine. So I connectedd DAQ assistant to "boolean to digital convertor" and then connect it to digital waveform graph but I don't see anything in the digital waveform graph. 

I don't konw whether I am doing it right or wrong. I just need rpm from this. 

[Patrick0418]

Hi, ashnu

I think you should put on your vi, and we can figure out what problems in your program.

Patrick

[ashnu]

Hello Patrick0418,

Thanks for the reply. Attached is the VI

[ashnu]

I am sorry the wires are broken in the previous vi, here is the snipshot of the vi.

[Hooovahh]

This is likely close to what you want.  You didn't provide enough information but it is a start.  You didn't say how often you expect to see pules.  If at your fastest spinning RPM you see a pulse once every 1ms, then you'll want to sample at least once every 0.1ms.  This is a constant on the block diagram which is sample rate, which I set to 10KHz.  You'll also need a samle duration and I set that to 1 second.  Too fast and you won't get accurate readings, too slow and there will be an averaging affect.  You also didn't say how many pulses you expect to see in one revolution.  I set it to 8 as a front panel control.  I also back saved into 2010 but I don't have 2010 so no idea if it works.

[Patrick0418]

Hi,

You can check that I think it is what you want.

http://www.ni.com/example/13580/en/

Patrick

[JÞB]

GEEZE Guys, you are doing that the hard way!

That M Series device  Has counters!

Set up a counter task (Frequency) and scale M=0.133333333 B=0 and scaled units are RPM (assuming 8 counts per rotation):smileywink:

[ashnu]

Thanks all for the reply : Smiley happy:

@ Hooovahh: I will try your VI for sure and tell what I found. 

@Patrick0418: I am using digital input but the link helps for analog input only.

@Jeff·Þ·Bohrer: The BNC 2110 has only CTR 0 OUT in the Trigger/Counter channel, so I don't know where to connect the digital output from picoturn to get a counter input.

[ashnu]

Hello Hooovahh,

I am right now getting an error -200284 (Some or all of samples requested have not yet been aquired...)

To give you more details on how long I am running the turbine: 

1. Just for less than a minute and running the turbine manually. I am expecting rpm of 500.

The maximum rpm that I can get from this device is 320,000.For the correct vane setting I am expecting 1 Pulse per revolution.

2.Could you please suggest me what to choose in the external clock dropdown?

[ashnu]

Hey guys!!

I solved the problem with the external clock by choosing PXI CLK 10 (that was in the manual of PXI-6251). Now when I run the program(given by Hooovahh), just one LED glows and the rpm is still 0.I am getting the graph as just one line and the whole line shifting to 0 and 1and not a square graph!!

Please give me some suggestions.