Hello,
There are a couple of notes that I would lilke
to add to the examples that you have submitted. The first is that
your program is configured to use a retriggerable finite counter as
your sample clock. You won't be able to do this with your application
because retriggerable finite counters require the use of both counters
on your DAQ card, and since you would like to use the other counter for
encoder measurements, your best bet would be to use continuous pulse
train generation, which only requires one counter, as your sample
clock. There is an example in the NI Example Finder (Help>>Find
Examples) called Gen Dig Pulse Train-Continous-Dig Start.vi that I
think will be perfect for your application.
For your
encoder task you should take a look at the example Meas Angular
Position-Buffered-Cont-Ext Clk.vi, which is also in the NI Example
Finder. Notice how they use a DAQmx Timing VI, which is necessary for
continuous encoder measurements. For the sample clock source of your
encoder measurement you will want to choose your devices internal
counter signal. For instance, if my device was Dev 1 and I was using
counter 0 as the counter for pulse train generation, then the sample
clock source would be "/Dev1/Ctr0InternalOutput". If you do not see
this option in the drop down menu for Sample Clock Source then you need
to right click on the drop down menu and select I/O Name Filtering. In
the Filter Names menu make sure that Include Advanced Terminals is
selected. Once you do this you should be able to find your counters
internal output in the drop down menu.
The last step is the analog output task. This
task doesn't require a sample clock because you will only be writing to
it after processing your counter measurements. You can get rid of the
DAQmx Timing VI as well as the Waveform Buffer Generation VI for this
task. This way, a write will occur only when the VI is called, which
is after the counter measurement is processed. Also, you want to make
sure that you are clearing your analog output task, which I noticed you
weren't doing in your original VI (input-output kp only with
clock-1.vi). A good example for this is the Gen Mult Volt Updates-SW Timed.vi from the example finder.
So in summation, each of those three examples is how you would want to configure each task. Each example also has a while loop in it, so you would want to combine them into one large while loop, which included your PID algorithm. Try this out and let me know if you have any questions or encounter any problems.
Regards,
. I did not use the example of analog output you suggested (although i tried it) because i think the one i use is simplier. I have attached the vi, in case i have something wrong that i haven't taken in mind and maybe helps. I don't know if there is a better way to wire the errors, for example i have seen some vi.s where the error wiring starts eg from the analog output, and passes through the CO pulse freq and the timing .vi. If you have some suggestions they are more than welcomed.