Correct way to index AUX channels?

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dmedine
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Joined: Sat Jan 16, 2016 12:22 am

Correct way to index AUX channels?

Post by dmedine »

I am writing a data acquisition client in C/C++ and I am a bit confused on this point. Here: https://www.biosemi.com/faq/make_own_ac ... ftware.htm (at the table on the bottom) the aux channel count appears to be 16 (after EEG and Ex), but here: https://www.biosemi.com/faq/adjust_samplerate.htm it appears to be 7. Then I read posts like this one: https://www.biosemi.nl/forum/viewtopic. ... nsor#p2450 and I see that the GSR channel is read from 2 aux channels (which makes sense as it is a comparative signal) but how do I know which channels to look at? Further confusion comes from the fact that there are 3 AUX ports on the front of the AD box (each having 7 pins). That doesn't square with the 16 channels indicated on the 'How can I make my own acquisition software?' FAQ or the 7 on the 'Is the sampling-rate adjustable on a BioSemi system?' FAQ. So what is correct? Why the discrepancy?

To make a long question short: if I have a sensor plugged into Aux 1 of my AD box, what channels do I need to look at in order to take a reading from the sensor?

Thanks in advance.

Coen
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Re: Correct way to index AUX channels?

Post by Coen »

The senso signals are sent from the AD-box in a block of 16 channels. Installed sensors generate data on dedicated channels in the block, uninstalled sensors generate flatliners. ActiView processes the 16 channels into 7 sensor channels (displayed and saved to BDF file). Inspect the LabVIEW source code for details about the channel order and processing.

Best regards, Coen (Biosemi)

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