Hello all,
Some background about my project. I am collecting data using multiple sensors. I have some sensors wired directly to laptops for data collection. Other sensors are wired to the USB-6225 data logger from NI. There is also a GPS timeserver being used which links all the laptops to the exact same time.
I am using the DAQexpress program to view and record the data logged on the USB-6225. I have a task set up for all my channels, but I do not have a .gvi file setup. I record data and the output file is a .tmds, I then export it to a .cvs file. I grab the initial timestamp from the original .tmds file (Figure 1). I don't use the timestamp outputted in the cvs file because it does not capture milliseconds. I then use the elapsed time outputted in the .cvs file (Figure 2) along with the initial timestamp to create my time vector for the NI logger.
My problem is there is a noticeable timeshift between sensors logged on the USB-6225 and sensors wired directly to laptops.The two data sets should sit directly on top of each other but do not (Figure 3). From troubleshooting I have ensured: the timeserver is working properly, the issue is not from my data analysis, the wiring to the USB-6225 is correct, and checked the channel naming in the DAQ express is correct.
I am still not positive if the problem is from the USB-6225 logger or DAQ express, but am running out of items to troubleshoot. Has anyone encountered a similar issue? Does anyone know if I am grabbing the initial timestamp correctly (from the .tmds file)? Also, does data collection start as soon as the timestamp is made in the tmds file, or is there some lag?
Thanks!
Courtney
