Beginner Questions about Stream Mode

Hello everyone.

First of all please excuse any mistakes I make, since I am a beginner in the use and programming of LabJack components as well as not a native enlish speaker.

I have a T7-Pro connect via USB to a Windows XP PC. I want/have to use Matlab to read out the data with stream mode. If I use the Matlab_LJM sample file SimpleStream.m to read out a single value, the maximum scanrate I can use is 99009, otherwise I get between 700-1400 skips per second. Since this value is close to the max sample rate of the T7, which is 100 ksamples/second, I am happy with it.

My problem begins when I want to read more than 1 value. For 2 values, my understanding of the manual tells me that the max sample rate per value should be 50 ksam/sec, or something close to 49000 on my PC. But the maximum I can use is 4755, a tenth of what I expected. Same thing with 3 values, the maximum scanrate I can use without error is 2427. If I go any higher, I get a STREAM_SCAN_OVERLAP error.

So my questions are:

1.) My first question is why I get the STREAM_SCAN_OVERLAP error while I am still far below the theoretical maximum and what I can do about it. I tried cahnging the Stream_resolution but to no avail. The Range is at -10V-10V.

2.) My second question is about the skipped Scans I get when I use a scan rate above 99009. I get the roughly the same total number of Skipped Scans if I use 99010 or 100000, which ranges from 700-1400 per read (or second).

3.) Is my understanding correct that when I use a scan rate of 99000, the T7 will 'measure' exactly 99000 times per second? So the scan rate I configure is the scan rate of the daq and not only the scan rate of the program?

I would like to thank everyone who can answer some of my questions in advance.

Sincerely Nikster