inter-channel delay and order of channel sampling for NI 9206 using Labview Signal Express

[petr07]

Hi all,

I am using an NI 9206 DAQ through Labview signal express software for multichannel impedance spectroscopy of solid oxide fuel cells.  For voltage measurements, I'm using twisted pair wires connected directly from the positive and negative terminals of the cell to individual channels of the 9206 DAQ set in differential configuration.  Current is being measured using a Tektronix TCP202 probe with Tektronix 1103 Power supply with BNC output to a 50 ohm resistor shunted across a channel of the 9206 again in differential configuration.

Frequencies of excitation range from 100 mHz to about 10 kHz and the DAQ is set to sample at 50 kHz.  At the higher frequency end of this excitation, the interchannel delay becomes very important as the impedance measurement will be significantly skewed if the delay between voltage and current sampling is not accounted for.  So, I am wondering what this delay is, and how it might depend on the sample rate selected, and if the order of channel sampling can be set through Labview Signal Express?  By order of channel sampling, I mean, will the DAQ sequentially sample according to channel number, e.g. ch0 ch1 ch2... or can I sample in an arbitrary order e.g. ch0 ch2 ch1 etc?

Thanks for any and all help,

Pete

[Carisa_L]

Hi Pete,

Thanks for writing on the NI forum. Unfortunately, LabVIEW SignalExpress is specifically meant for quickly acquiring, analyzing, and presenting data, which means it is limited when it comes to any further customization. On the bright side, you can achieve what you're looking for with LabVIEW. I have placed a couple of links to some resources below. Hope this helps.

How Do I Increase Interchannel Delay Using NI-DAQmx or Traditional NI-DAQ (Legacy)?: http://digital.ni.com/public.nsf/allkb/65E7445DB1AA5DC586256A410058697B

Minimum and Maximum Values for the Interchannel Delay Setting: http://digital.ni.com/public.nsf/websearch/9AE87416C8792FC286256D190058C7D3?OpenDocument

Convert Clock and Interchannel Delay with NI-DAQmx: http://zone.ni.com/devzone/cda/epd/p/id/1691

Best,

Carisa Leal