random square wave

[Prince Boeing]

i have a pxi-6289 m series multifunction daq card. i wish to generate a square wave of +/-5 V. However, i do not wish to have a fixed period/frequency for it. That is, i wish to have something as follow:

for time 0 - 1s, period of square wave is 50ms;

for time 1 - 3s, period of square wave is 500ms;

for time 3 - 5s, period of square wave is 25ms;

for time 5 - 6s, period of square wave is 1s;

for time 6 - 7.5s, period of square wave is 100ms;

for time 7.5s - 8s, period of square wave is 10ms;

for time 8 - 10s, period of square wave is 250ms.

In short, i wish to be have different periods of the square wave in a 10s waveform. Is such design feasible? I also have a pxi-6551 digital i/o card. please advise and thank you in advance.

[src42]

This is definitely possible. I use WaveMetrics' Igor Pro for all my NIDAQ mx data acquisition tasks, along with its NIDAQ Tools MX extension. All you have to do is create in Igor Pro whatever output waveform (array) you need, and use this as a parameter to the DAQmx_WaveformGen command.

I am attaching a graph of such a waveform that meets your specifications. Resolution limits of the screen display blur the png figure in the high-frequency regions, but be assured that a zoomed display shows your required periodicities.

[src42]

I forgot to add you +/- 5V scaling. See the new figure. BTW, this waveform uses 0.5ms sampling increments. You can change this if desired.