I need two pulses from one pulse. The pulse is not 50 % duty cycle

[pnielsen@gplains.com]

I have a 9 second ON pulse and a OFF period ? I need to create a pulse for the ON time. And I need a pulse for the OFF time. I need to monitor a valve in the ON state and the OFF state. I just need a pulse for the ON state and the OFF state to write to a file.

Philip Nielsen

ASC

[samantham]

Hello,

It looks like you have one signal that you want to monitor.  When there has been a change from high to low or low to high you want to produce a pulse.  Thus, there are two periods (pulses) for one period on the incoming signal.  Does this resulting signal of two pulses for every one pulse need to be output or just data to write to file?  I am also interested if you already have any DAQ hardware or if you are looking for a recommendation.  Please let me know. 

On many of your Multi Function DAQ device we have a Change Detection task that will produce a pulse for changes as describes above.  How many signals will you need to monitor ... one or more?  The Change Detection task is supported through the NI-DAQmx driver and NI DAQ hardware.  Please clarify and I can help with a hardware recommendation and software solution.  The NI-DAQmx driver downloads with a large amount of examples.  One examples that relates is title Read Dig Chan - Change Detection.  If you have Chance Labview and the DAQmx driver you will be able to open this example.  Please also let me know if you have Labview or plan to use a text base API.

[pnielsen@gplains.com]

I am using the NI 6009 hardware. The examples say it can take rising examples. But I found out the hard way the 6009 will not take rising edges. I am trying to write to a file during the ON time and the OFF time.

Thanks

Philip

[samantham]

Hello,

The USB-6009 does not support the Change Detection task that I had mentioned before.  The counter measurements are limited to counting events on falling edges and the digital lines are software timed.  With software timed DIO lines, the application will depend on software procession of incoming digital data.  Are you okay with software processing and some of the drawbacks of it not being deterministic?  For your application, we might want to consider another device if software processing is not an option.  Please give me some feedback.

[pnielsen@gplains.com]

I need to write to a file during the high state and the low state. I am opening a jet bypas valve recording the data. Then I close the valve and recond data again. I will be at labview trainging Sept 22. Maybe one of the teachers could help.

Philip

[hoffiz]

Hi Philip,

As Samantha said this is going to be a software timed DIO
task. There are already examples that will allow you to do static DIO with the
6009. Is there any chance you can answer Sam’s question, since they are necessary
to give a better and more complete solution.

Message Edited by Jaime F on 09-16-2008 01:48 PM

[pnielsen@gplains.com]

I have created on output signal on Ao0 and Ao1. They are about 180 degrees out of phase of each other. The one pulse has its ON time and OFF time from the same pulse. I am measureing air pressure throgh a valve open and closed. I am trying to create two writes to a file. One when the relay is on and one for the off time.

Philip Nielsen