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generating long pulse on E series board
shiva
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02-04-2002 04:43 PM
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I am trying to generate a long digital pulse on a PCI-6053E board, using Borland's Delphi 4 and NI-DAQ functions. The pulse needs to be synch'ed to a clocked waveform being output on both analog channels with a specific number of points Nout. Ideally, if there were a digital signal which went high or low over the exact period of time the DACs were being updated with Nout points, this would be perfect. However, I have not been able to find such a TTL signal in the 6053 documentation.
Another way I thought of doing this is to generate an output pulse using one of the general purpose counters, by counting the number of UPDATE signals from the DACs until it reaches Nout. Both the timer and the waveform generation could be ti
ed to the same trigger. However, the number of output points is typically larger than the 24-bit resolution of the STC timers, so this will not work with a single timer. I could try and concatenate two timers, by sending the TC signal of the first to the second, and thereby extending the range. However, I have to use the output of the second timer, which does not give me enough resolution. For example, if the update signal occurs every 10 microsec, the first counter will roll over every 2^24 x 10 microsec, which is the resolution of the second counter. If I want to monitor and turn off my digital signal on the scale of fractions of an update signal, this will not work if my digital signal is connected to the output of the second timer.
Any ideas would be appreciated.
Another way I thought of doing this is to generate an output pulse using one of the general purpose counters, by counting the number of UPDATE signals from the DACs until it reaches Nout. Both the timer and the waveform generation could be ti
ed to the same trigger. However, the number of output points is typically larger than the 24-bit resolution of the STC timers, so this will not work with a single timer. I could try and concatenate two timers, by sending the TC signal of the first to the second, and thereby extending the range. However, I have to use the output of the second timer, which does not give me enough resolution. For example, if the update signal occurs every 10 microsec, the first counter will roll over every 2^24 x 10 microsec, which is the resolution of the second counter. If I want to monitor and turn off my digital signal on the scale of fractions of an update signal, this will not work if my digital signal is connected to the output of the second timer.
Any ideas would be appreciated.
John N
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02-05-2002 04:45 PM
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Hi Shiva,
Just a short suggestion - if you configure your first counter for a pulse train generation, then you don't have to reach a full count of the timer before updating the second counter. For instance, you could set pulse specs to be low for 5 source pulses and then high for 5 source pulses. Thus your second counter would get updated every 10 pulses of your first counter. You could customize this to have just about any pulse rate you want coming into your second counter.
Just a short suggestion - if you configure your first counter for a pulse train generation, then you don't have to reach a full count of the timer before updating the second counter. For instance, you could set pulse specs to be low for 5 source pulses and then high for 5 source pulses. Thus your second counter would get updated every 10 pulses of your first counter. You could customize this to have just about any pulse rate you want coming into your second counter.
