09-26-2011 04:15 AM
I use NI PCI 6259.
I connect 2 resistor on Breadboard (please see attached file).
AO input is SRE and AIs are Differential.
When I applied a SIN waveform to AO with 1 kHz frequency the AIs are correct and approximately without differential phase.
But When I use a SIN waveform with 100 kHz frequency the AIs are not correct and they have a differential phase.
Would you please tell me do it is because of capacitance phenomena in Breadboard in high frequency or it is because of AI input impedances or both?
Would you please tell me how can I correct this problem?
Thanks for your time and attention.
Best regards
09-27-2011 10:15 AM
What DAQ board are you using? If it is an E, M, or X Series DAQ board then the inputs are probably not simultaneously sampled. This means that at higher frequencies the difference in voltage over the time it takes to switch channels and sample would make it look like the two channels are out of phase. If this is a big issue for your application we have boards that simultaneously sample all inputs. By default the AI Convert clock is at its maximum frequency.
For more information check out this thread: What is the timing relationship between the input MUX and the convert clock in DAQmx there is a bunch of really good information about the AI convert clock.
Regards,
Matt M.
09-27-2011 10:25 AM
Thank you
I use NI PCI 6259 and it is an M series.
Doesn’t it have a simultaneously sampling?
09-27-2011 10:39 AM
Unfortunately no, the PCI-6259 does not have the ability to simultaneously sample.
Here is a link to the product page: NI PCI-6259
If you look under the specifications tab you will see:
Simultaneous Sampling | No |
Regards,
Matt M.
09-27-2011 10:49 AM
Thank you
So, Is there a solution for this problem using NI PCI 6259 in 100kHz frequcncy?