Data aquisition with DT9836 and 1808X

[Matt80]

Hi,

in the digilent shop, the 1808X is recommended as successor of the DT9836. DT9836 provides the option to define individual software buffers to write in and read them out by event-handling (buffer_done_event). What possibilities are there with the 1808X to combine e.g. counter and encoder values with analog input values and read them out simultaneously and seamless, as it appears, there is no buffer-solution anymore.

[Fausto]

Hello @Matt80.

For the USB-1808X, use the DAQ Input functions to simultaneously capture capture combined data from different subsystems.  Also, for MCC USB devices like the USB-1808X, only one large buffer is used.  The code ping pongs between the lower half and upper half of the buffer.  Take a look at the attached VB.NET and C#.NET examples.  The attached examples demonstrate how to read a buffer that is being filled continuously with live data.

The functionality is as follows, the acquisition puts data into a continuously looping buffer and the program retrieves it one half buffer at a time. The continuous mode is set using the Scan Options enumeration Background and Continuous. Data is collected by ping-pongs between the lower half then the upper, looping fast enough to keep up. Care should be taken that data doesn't come in so fast that the program fails to keep up. When this happens a buffer overrun occurs which is the condition where unread data gets overwritten. 

Universal Library for Windows Help 

 

Regards,

Fausto

AinScanBackgroundContinuousScan.zip

VBNET_2013_Cont_Background_Scaled_Data.zip