Digital and Analog Signal Mixing

Digital and Analog Signal Mixing

Post by Mustang M » Wed, 20 Feb 2008 12:10:05


Hello,
 
I am trying to sum a digital signal with an analog signal using LabVIEW. Both signals are sampling continuously at a 1kHz rate with a buffer size of 100 samples (defaulted values for the Express VI), and I am displaying them to the screen in real time and writing them to a file for later manipulation. The hardware associated with this problem is a PCI 6251 board and a BNC 2110 connector block. I am having multiple problems.
 
1. To start, I can not sum the two signals together when I use the digital signal configured as a counter. I put it and the analog signal on the same external clock (an external waveform generator sending a 1kHz square wave), but ther is an issue at the summing block - "dt of signals is different." How can this be?
 
2. The analog signal displays a time history as long as I want. This means I can display 5 seconds of data on the screen even though my buffer holds 0.1 seconds of data. I have not found a way to force the digital signal to do the same. Is there a way to do this?
 

3. I think I can configure the counter as four separate digital signals. If I decide to use the four separate digital inputs to "create" my final digital input, can I manipulate these signals using the math functions to build my counter? Would I be able to eliminate/sidestep problems 1 and 2 if I did that?
 
Any information would be greatly appreciated. Thank you for your help!
 
Ty