Why do I receive an error while using the GETDATA function with the Data Acquisition Toolbox 2.5.1 (R14SP1)?

I am able to successfully set up and start my analog input device. When I attempt to access the device using the GETDATA function, I receive the following error:

 internal GETDATA error: Trigger start not in buffer

After this error, the SamplesAvailable property of my device decreases, but not by the amount I specify with GETDATA. I am able to view the results using PEEKDATA.

Answer 1

[MathWorks Support Team]

This bug has been fixed in Release 14 Service Pack 3 (R14SP3). For previous product releases, read below for any possible workarounds:

We have verified this as a bug in the Data Acquisition Toolbox 2.5.1 (R14SP1) in the way the engine works with an external clock. When working with an external clock, the engine sometimes makes errors in determining when a particular hardware trigger took place.

When a device is operating with external clocking, it is hard for the software to determine when a trigger or a sample occurred. The toolbox uses the SampleRate property to estimate when a sample or trigger occurred. To work around this issue, set the SampleRate property to a value equal or greater than the external clock rate.