Jump to content

As of July 17, 2015, the LabJack forums here at forums.labjack.com are shut down. New registrations, topics, and replies are disabled. All forums are in a read-only state for archive purposes.

Please visit our current forums at labjack.com/forums to view and make new posts. To post on the current forums, use your labjack.com login account. Your old LabJack forums login credentials have been retired. There are no longer separate logins for labjack.com and LabJack forums.


Photo

High-level application question


  • Please log in to reply
4 replies to this topic

#1 rayh

rayh
  • Members
  • 3 posts

Posted 12 May 2014 - 12:53 PM

Hello!

 

I have a need to generate a one-shot pulse train of a settable numer of pulses.  I also need to be able to vary the duty cycle of the pulse train, but not withing any one sequence. 

 

The problem is that I need to trigger the occurrence of the pulse train with an input signal that is timing critical and cannot involve the host computer or the delays over USB.  Once set up, I need the input to trigger the output by itself until told to stop

 

Is this possible with the U3, or any of the other models?  I am a bit confused with DAQFactory and the other software capabilities as to whether I can just set a few parameters via the computer interface (#pulses, duty cycle, etc.) and then just let the labjack operate on it's own, syncing tne output pulses with the one input trigger.

 

Any help appreciated!

 

Ray



#2 LabJack Support

LabJack Support
  • Admin
  • 8677 posts

Posted 12 May 2014 - 12:58 PM

 

 

The problem is that I need to trigger the occurrence of the pulse train with an input signal that is timing critical and cannot involve the host computer or the delays over USB. 

 

With the U3, I can only think of 1 option.  You start 2 timers in PWM and STOP mode, but put some sort of external latching switch on the PWM output so it does not get through until the trigger happens.

 

With the T7, you could use scripting to do what you want:

 

http://labjack.com/s...ts/t7/scripting



#3 rayh

rayh
  • Members
  • 3 posts

Posted 13 May 2014 - 04:02 AM

Thank you!

Is the scripting (alpha?) and it's functionality something that should be considered as stable, etc. for a long-term project?



#4 LabJack Support

LabJack Support
  • Admin
  • 8677 posts

Posted 13 May 2014 - 07:45 AM

Since it is the alpha/beta state, there is the possibility of minor changes to behaviors and register names.

 

In your case, you have a pretty basic script.  We can support you now, and any possible changes should be minor details that might require changes to your script if you update firmware, but don't really impact the functionality of your script.

 

Your script needs to do 2 things that are basic operations of the device:

 

    1.  Read the state of a digital input or the value of a counter (your trigger).

    2.  Output a pulse train.

 

These are basic operations of the T7 done with normal register reads and writes.  The same register reads & writes whether you do them from software on some host or from script.  All the script is doing that is unique, is some sort of conditional watching #1 and when it sees what you want doing #2.



#5 rayh

rayh
  • Members
  • 3 posts

Posted 13 May 2014 - 07:56 AM

Thank you again!!!




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users