We finally are getting back to diagnosing our data collection problem. We have confirmed that the issue is not with the incoming signal. The issue only appears with the board installed on the new PC. We have two identical DT3010 boards, both of which work on the old PC and both exhibit the same symptoms on the new PC. The same gap in the signal also appears when using other sensors.
I have a suspicion that the issue is related to buffering. The original programmer is no longer available, and I am not familiar with every aspect of the program. The test is recording a pressure rise on a single analog channel. The acquisition triggers on the pressure signal (the trigger threshold is set to 0.5 V). A typical data acquisition uses n buffers, each of which is set to hold 4 kSamples. On the legacy PC, a test set up for 4 buffers will collect a bit less than 16 kSamples (the number of samples captured varies from one test to the next). If we change the parameters to include 5 buffers or increase the length of the buffers, the test records more samples. Each data file will contain a number of samples a bit smaller than the size of the buffer times the number of buffers. A comment in the code notes that buffer 0 is the pretrigger buffer, buffer 1 is the trigger buffer, and all subsequent buffers are postrigger.
However, when we run a test on the new PC the data file contains an exact number of data points that is equal to (n-1)buffers * buffer size. For example, if the settings call for 6 buffers with 4 kSamples/buffer, we get exactly 20 kSamples (we would expect more samples between 20k and 24k). The worst part is that the second buffer (trigger buffer?) worth of data is all zero. From sample 1-4,000 we have analog input values that seem good. From 4,001-8,000 everything is zero. From 8,001 to the end seems ok.
Why would an empty buffer get inserted in the data? Why would the legacy system collect more samples? As far as we can tell, the settings related to data acquisition are the same on both the new and the legacy PC.