Hello,
I have a question regarding the signal input to LabView via the USB interface.
Setup: Manually constructed sinus wave (colpitt - oscillator) as an analog input to an P8055-1 Velleman PIC card. (PIC16C745). The PIC card ADC:s this to an 8 bit signal and outputs it to the USB interface and then sends it via the USB cable to the USB PC port.
I have downloaded an VI for the P8055 card, and it shows fine in LabView. Now the problem is that the analog signal that i am receiving shows only the amplitude of the signal and no time stamps. So the signal cant be analyzed in a proper maner, at least when it comes to reading a sinus wave signal.
What i have read on this forum and other sites is that you really cant measure any frequencies beyond the USB port... that is 8ms - 10ms (125-100Hz). I am confused about sample rates and frequencies...
The real question is. What am i doing wrong ? Can i use the USB for measuring of high frequencies ? If so, what is the range ? Am i using the right VI driver in LabView ? Shall i discard the P8055 VI and make a new with raw USB measurements ?
Are there any alternatives... like measure with a serial or parallel port ? Should i use the USART (have not dug into this yet) communication with the PC ? Are there any way to clock the time with the 4Mhz clock on the PIC and use this to timestamp in LabView ? (like sending a pulse every loop, and measure the time of this loop)
Thanks for any reply of any kind that brings me closer to get some measuring within a resonable cost....
// Roger
