PWM read vi

[JTDWAB]

I am trying to read a PWM input (at TTL levels) using a 6023E multifunction DAQ. All of the sample VI I've downloaded and those functions built into labview work one time then end. When I try and run them continuously they error out I believe because the signal to the counter is high when the start up on each loop. What can I do to provide a continous updating reading of the PWM signal I am monitoring?

[Spencer S.]

JTDWAB,

I am assuming that you are performing a pulse-width measurement on the PWM signal. The following continuous, buffered examples are available through LabVIEW's example finder:

NI-DAQmx (Requires LabVIEW 7.0 or later)
Meas Pulse Width-Buffered-Cont.vi

Traditional NI-DAQ
Measure Buffered Pulse (DAQ-STC).vi

Good luck with your application.

Spencer S.

[JTDWAB]

Thank you for your guidence I have the counter running however I have hit a new snag. The VI I want to read the PWM signal (500hz, 5-95% PWM) also is reading 6 analog voltages at 500 hz sample rate. I cannot find an example describing how to inciate the counter and the AI to both output at the same time. Is this possible and is their an example I could follow?

[Spencer S.]

JTDWAB,

It should be fairly easy to combine a pulse-width measurement example with an analog input example to create your desired application. Numerous analog input examples are available through the LabVIEW example finder.

Spencer S.

[JTDWAB]

I am able to configure a VI for the analog channels and 1 for the counter channel. I have not figured out how to get both data at the same time. I know I can't use two DAQ assists at the same time. I have tried them as global channel reads however it only works when I don't have the counter selected. When I do this none of the channels read at all. Where can I find an example of running both at the same time.

[Spencer S.]

JTDWAB,

When you say that you want to "get" both counter (PWM) data and analog data at the same time, what exactly do you mean? Do you want to synchronize these measurements, or do you simply want them to both be performed within the same VI?

Spencer S.

[JTDWAB]

I would like them to be synchronized. The equipment I am testing performs various functions based on the PWM signal sent to it. I want to know what is coming in so that I can determine if what I am getting out is correct.

[Spencer S.]

What type of synchronization do you want to achieve? Do you want to correlate each pulse width measurement with an analog input sample? Do you have a VI that you are currently working on that you could post?

Spencer S.