Difficulty in Recording TTL Pulses

[Amir A]

Hi,
I'm having difficulty in recording TTL pulses generated using a Pulse-Generator.

My program works by first generating a square pulse and sending it to analog output channel 0 of my PCI 6024 DAQ card. When this square pulse is detected by the Pulse Generator, the latter produces a TTL pulse (high 4 V for 0.1 msec) on its two output channels. I am taking the output from these channels and feeding them into analog input channels 0 and 1 on the DAQ card. The pulses are then viewed using a waveform graph.

When I run the application, I am only able to see a square pulse on one of the channels. My sampling rate is 10kHz. I thought that the channel in which I cant observe the pulse was bad but when I attempted to record fr
om a different analog input channel, I again did not get the pulse. I should note that on one channel I can see the pulse on the graph but the other channel only gives noise. I've fed the output from the pulse generator to an oscilloscope on which both square pulses are visible.

If anyone could give me any ideas about why I can see the signals on an oscilloscope but only one from the computer screen, it would be most appreciated. Thanks.

[Dennis_Knutson]

Using one AI Waveform Scan to acquire three channels might be a better way to go but if don't want to do that, at least use the error in/error out connections to give you some data flow to see if anything is generating an error. There's no reason that the AO will execute before any of the AIs. Also, since you actually have three AI Waveform Scans, I don't understand what two channels you are refering to.