Question about analogue inputs on NI SB-RIO 9636

[Gusss]

I have a question about the NI SB-RIO 9636 development board . I want to several sample small voltages in the region of 20 - 200 mv . Ideally I would like to record up to 16 channels simultaneously into labview. An engineer has told me this is possible with this board yet on reading the specifications it says :

Analog Input
Channels	16
Simultaneous Sampling	No

So does this mean I cannot sample 16 channels seperately and simultaneously into labview ? I know it seems like a silly question but if not it means the engineer is wrong !

[Gusss]

I think Ive just worked it out - I dont need true simultaneous sampling right ? I can just take samples on the 16 different channels at slightly different times meaning that I get the same resolution on all channels - its just the samples are taken sequentially from the different channels instead of all at the same time - ie I have a maximum resolution of 16 samples - which is more than good enough - correct ?

[Spex]

Hi Gusss,

Sounds like you are on the right track.  The sbRIO-9636 uses a multiplexed ADC to acheive the 16 channels via one converter.  While this means that the channels cannot be sampled simultaneously, you can scan through the channels quickly to get data that is near simultaneous.  The sbRIO-9636 user manual indicates that the maximum aggregate sampling rate of the analog input channels is 200kS/s, indicating that the minimum time between samples is 5 microseconds.

In case anything isn't clear, the tutorial below gives a graphical representation of the difference in sampling behavior between simultaneously sampled inputs versus multiplexed.

Multiplexed Versus Simultaneous Sampling

Cheers,

[MW_BKT]

Hi, 

I'm using sbRIO9636 and want to read anaglogue channels, I want to know that how can i select the range of analogue channel ? and also i've to read multiple channels with specific time, How can i calculate conversion and sampling time?

Can anyone guide me ?

Regards