Dan Scoville
2006-08-14 12:10:10 UTC
Hi,
I am trying to use Labview 8.0 software and a NI USB-6251 board to fire 4 solenoids. The solenoids need to be fired either all at once (0mS between each solenoid) or at some specified delay interval between each solenoid. The delay intervals start at 5mS delay between each solenoid and increase from there in 5mS increments. Therefore a 5mS delayed solenoid firing would consist of the 1st solenoid firing at 0mS, the second solenoid firing at 5mS, the thrid solenoid firing at 10ms and the 4th solenoid firing at 15mS.
To accomplish this I used a timed loop structure and 4 timed sequence structures (see attached VI). I used the t0 pin of each sequence to specify what the delay times should be between each solenoid firing. The problem I am having is that at low delay times between solenoids the timing becomes quite inaccurate as veiwed by a scope (mainly at 0mS, 5mS, 10mS and 15 mS delays.) An example is that if I request a delay of 5mS the solenoids may fire erratically with a delay around 10-15ms. I have looked at the expected loop start and actual loop start terminal of the timed structure and they appear to start on the correct tick number (ie a 5mS delay gives a 0, 5, 10, and 15 for actual start times for each timed sequence.)
How can I make the timing correct?
Thanks
Dan
Air_Array51.vi:
http://forums.ni.com/attachments/ni/70/5329/1/Air_Array51.vi
I am trying to use Labview 8.0 software and a NI USB-6251 board to fire 4 solenoids. The solenoids need to be fired either all at once (0mS between each solenoid) or at some specified delay interval between each solenoid. The delay intervals start at 5mS delay between each solenoid and increase from there in 5mS increments. Therefore a 5mS delayed solenoid firing would consist of the 1st solenoid firing at 0mS, the second solenoid firing at 5mS, the thrid solenoid firing at 10ms and the 4th solenoid firing at 15mS.
To accomplish this I used a timed loop structure and 4 timed sequence structures (see attached VI). I used the t0 pin of each sequence to specify what the delay times should be between each solenoid firing. The problem I am having is that at low delay times between solenoids the timing becomes quite inaccurate as veiwed by a scope (mainly at 0mS, 5mS, 10mS and 15 mS delays.) An example is that if I request a delay of 5mS the solenoids may fire erratically with a delay around 10-15ms. I have looked at the expected loop start and actual loop start terminal of the timed structure and they appear to start on the correct tick number (ie a 5mS delay gives a 0, 5, 10, and 15 for actual start times for each timed sequence.)
How can I make the timing correct?
Thanks
Dan
Air_Array51.vi:
http://forums.ni.com/attachments/ni/70/5329/1/Air_Array51.vi