a delay of 20 microseconds is very quick for Labview, I see 3 options:
1. Start analog aquisition before the Digital select happens, and record a second channel which reads a triggering signal. After you finish reading the signal, use the second channel to tell when the analog reading was correct. Some people have done this using an external chip, you set all digital addressing lines into a latch chip, then use 1 extra digital output to inhibit the digital addressing, and you just read the digital output as the second triggering channel.
2. Most of the cards you listed have extra digital i/o triggering lines, try to use one of them as a trigger. Or you can try digging into the advanced analog aquisition VI's. You can program most NI cards to aquire 1 analog sig
nal based on a trigger from another analog input. try the link below:
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3. use labview RT, this would take out any delay the OS has
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