Measurement Computing DASYLab - Manual (Page 51)

DasyLab - Standard Driver 989693 Configuring DASYLab for WaveBook A-15
FIFO Settings (for WBK30 Option)
The FIFO Settings control will display the FIFO type and size of the unit if it is on-line.
If a programmable FIFO is installed (WBK30) it will allow for long acquisitions at speeds greater than the
port throughput. If an infinite acquisition is attempted with a slow port, a FIFO overrun will eventually
occur. Fixed length acquisitions in the series modes will never overrun if they fit within the FIFO.
Note: Downloading a full 64Meg Sample FIFO with a slow 100Khz parallel port can take over 10
minutes.
The following options are available for enhanced FIFOs. Using FIFO as primary buffer will:
• prevent DASYLab buffer overruns by only transferring data into DASYLab when there is room for it.
• enable Pre/Post acquisitions to buffer everything on the hardware until the acquisition completes.
After the acquisition completes, it is downloaded as DASYLab makes room for it. This allows use of the
devices' maximum sample rate regardless of the port throughput or worksheet complexity.
Standard FIFO usage can cause DASYLab buffer overruns during complex
worksheets. Standard Pre-Trigger acquisitions require that all data be streamed into
DASYLab, and are thus limited to the parallel port throughput speed.
In regard to transferring all good data from FIFO in event of a buffer over-run:
Notification of the over-run will be held until all data has been transferred to DASYLab. Notification of
the over-run will be present in DASYLab’s onscreen status bar, but the worksheet will not stop until all
readings have been downloaded. This differs from typically seen actions; i.e., immediate stop followed by
an error signal and FIFO flush.