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Freqout on multiple timers: how to start stop individual outputs?

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#1 twm

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Posted 11 October 2012 - 03:07 AM

after some testing i got it to work to output different frequencies with 3 active timers.
I can change individual frequencies at runtime:
LJUD.AddRequest(u6.ljhandle, LJUD.IO.PUT_TIMER_VALUE, 1, divider, 0, 0);

when i try to stop one of the outputs:
LJUD.AddRequest(u6.ljhandle, LJUD.IO.PUT_COUNTER_ENABLE, 1, 0, 0, 0);
All 3 counters stop. if i try to restart:
LJUD.AddRequest(u6.ljhandle, LJUD.IO.PUT_COUNTER_ENABLE, 1, 1, 0, 0);
The Labjack hangs up. If i do a full reinitialization of all three timers after the disable command, it doesn't hang up.

So: What is the best way to start stop the frequency output individually on the channels without stopping / disturbing the other channels? (I would like to control some stepper motors with the Freqout feature)

Best regards

#2 LabJack Support

LabJack Support
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Posted 11 October 2012 - 02:53 PM

I am not sure why disabling or enabling Counter1 is affecting your timers, but that is not what you want anyway.

To enable and disable timers you use iotype LJ_ioPUT_CONFIG with special channel LJ_chNUMBER_TIMERS_ENABLED:


For example, to enable 3 timers (Timer0-Timer2), you could do something like:

ePut (lngHandle, LJ_ioPUT_CONFIG, LJ_chNUMBER_TIMERS_ENABLED, 3, 0);
If you want to disable 1 timer, then Timer2 is the only one you can disable leaving Timer0 and Timer1:

ePut (lngHandle, LJ_ioPUT_CONFIG, LJ_chNUMBER_TIMERS_ENABLED, 2, 0);
A better way to "stop" an output, is to change the mode of the particular timer you want to stop to some input mode. For example, you can have all 3 timers enabled, and change the mode of Timer1 to make it stop outputting:

ePut (lngHandle, LJ_ioPUT_TIMER_MODE, 1, LJ_tmRISINGEDGES16, 0);

I suggest you start by trying to do what you want in the test panel in LJControlPanel, before doing it in code.

#3 twm

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Posted 15 October 2012 - 08:21 AM

thanks for your reply. Although i found the answer by myself before the post was published, changing the timer mode is the right solution. I enable 3 timers and can start stop the frequency output individually by changing the timer-mode. This doesn't affect the other timers in contrast to the enable/disable i previous tried. Regards, Ben

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