USB-1608GX drops occasionally drops first sample when run at high frequencies in continuous mode.

[ticarus]

When using the uldaq library in Linux, I find that the first sample is occasionally missing when I run the DAQ in continuous mode reading multiple channels at an sampling frequency of approximately 2 kHz or higher.

For example, if I read from channels 0, 1, and 2, the channel 1 data would be reported as channel 0, etc.

[Fausto]

Hello @ticarus.

Can you quantify occasionally?  Is there a particular configuration that reproduces the issue more often than others?  Are you using a new USB-1608GX module or is the history unknown?  What is the serial number on the backside label?  If it is not a new module, please connect the USB-1608GX to a Windows OS system which has MCC's InstaCal software installed.  Using InstaCal, what is the module's firmware version?

Are the analog input channels configured in differential or single-ended mode?  Use InstaCal to verify.

Are you using a hardware trigger to start the acquisition?

Are your initial data points as follows:  CH1, CH1, CH2, CH0, CH1, CH2, CH0, CH1, CH2, etc.?

Are you programming in C or Python and do you have a simplified example to share for testing purposes?

Regards,

Fausto