problem with RSE and NRSE

[nickev]

i'm using a 6052E pci card and I'm sampling it at 20kHz per channel. it works fine when i set the input to RSE,

but when i set it to NRSE it works for about 10 seconds and then all the inputs drop to zero. The aisense and aignd pins are shorted together.       The reason i'm bothering is i understood NRSE is a better setting than RSE,

as its less noisy. Is this correct? my input is coming from 16 avalanche photodiodes, and the output from these can be anything from -5v to +  5v.

the code i'm using is:

DAQmxCreateAIVoltageChan (taskHandle_alog_in,

"Dev1/ai0,Dev1/ai1,Dev1/ai2,Dev1/ai3,Dev1/ai4,Dev1/ai5,Dev1/ai6,Dev1/ai7,Dev1/ai8,Dev1/ai9,Dev1/ai10,Dev1/ai11,Dev1/ai12,Dev1/ai13,Dev1/ai14,Dev1/ai15",

"", DAQmx_Val_NRSE, -5.0, +5.0,

DAQmx_Val_Volts, NULL);

DAQmxCfgSampClkTiming(taskHandle_alog_in,"",samplingFreq,DAQmx_Val_Rising,DAQmx_Val_ContSamps,dwNumScans);

DAQmxReadAnalogF64 (taskHandle_alog_in, dwNumScans, 10.0,

DAQmx_Val_GroupByChannel, input_data,

dwNumScans*dwNumCh, &numRead, NULL);

any advice would be appreciated.

[Tom.]

Hello Nick,

First of all look at this link to ensure you have selected the correct measurement configuration for your system.

Secondly do the 0 values appear after 10 seconds everytime or does it vary? Does it occur after a certain number of samples have been read? Also have you probed the signal entering the card to ensure it is a measurement problem and not a sensor one?

Tom
NIUK