how to use labview to read an encoder using a multimeter?

[NIquist]

I didn't mean to sound MEAN.  I just thought it was humorous that you thought a VI would be available for an application so... unusual.  And you never know, many of us (including me) do play with cobbling up weird combinations of instruments just to see what we can get away with.

I made an error in my calculation as well so what do I know? .  Forgot to convert minutes into seconds for Hertz as noted above.

I also wasn't joking about the parallel port.  Do you have one on your PC?  It can read the TTL signals of your encoder index and it's FREE.

Check out the example: Help > Find Examples... > Hardware In & Out > General > Parallel Port Read and Write Loop.vi

Port Spec link: http://www.circlemud.org/jelson/software/parapin/docs/node2.html

EDIT:  There is a tab in the example VI that also shows the pinout of the port on the second page.

[sitzikbs]

ok, you will be happy to know that i found an MCC DAQ usb-1408fs for the job . it has :

8 analog inputs

16 digital I/O

1 event counter

2 analog outputs

48 kS/s sampling

http://www.mccdaq.com/usb-data-acquisition/USB-1408FS.aspx

i installed the labview libraries. 

so how do i do this ?  

ill remind the requirement - i need to count rounds with an encoder (rpm will be nice to have as well but not a must). I also need to measure force with a load cell (it simply gives a dc volt output in direct proportion to the load). would the DAQ know how to read the load cell as well? 

i saw thatit has a 5V dc output. do yuo think i can connect both sensor to the same output?

[johnsold]

I did not register on MCC's wweb site, so I cannot see the specifications for that device.  It may not be the easiest device to use but likely will be a better choice than the DMM and oscilloscope you were trying to use earlier.

You can measure the load cell output voltage and convert the voltage to force by multiplying by the load cell scaling factor.

If the event counter is capable of making frequency or period measurements (as opposed to simply counting events), you can get the rpm measurment by scaling the frequency according to the number of pulses per revolution.

You will need to check the specifications to see how much current is available from the 5 V output and how much is required by your sensors.  For simple sensors without intelligence built in, you will probably have enough current.

Lynn

[sitzikbs]

thanks so, if i understand correctly - the load cell i plug into one of the analog channels.

i dont think you need to register to see the specifications. did my link not work ? 

im not sure which event counter you mean ? i have 16 digital channels arnt they good?  cant i simply program in labview to calculate the speed? 

[johnsold]

To get the User's Manual or the detailed specs you need to register or log in.  Your link is fine.

If the digital I/O is hardware timed, you can use that.  If it is software timed (on demand), then it will likely be too slow and have too much jitter to get good timing data.

Yes, the laod cell will connect to an analog channel.

Lynn