HP E1433A, User Manual, Page: 70 / 222

Limit on Queuing of Data
In overlap block mode, a number of trigger events may be queued up
before the host reads the data for those triggers. The host may get further
and further behind the data acquisition.
However, if the host gets far enough behind that the FIFO fills up, data
acquisition must momentarily stop and wait for data to get transferred to
the host. This places a limit on how far in time the host can be behind the
data acquisition. By setting the size of the FIFO, is you can control how
far behind the host can get.
Making Overlap Block Mode Act Like Traditional Block Mode
If the FIFO size is set the same as the block size, or if the number of
pending triggers is limited to zero, then overlap block mode becomes
identical to traditional block mode.
Making Overlap Block Act Like Continuous Mode
If the module is in auto-arm and auto-trigger mode, then overlap block
mode becomes nearly the same as continuous mode.
One difference is that traditional continuous mode has a single arm and
trigger, while overlap block mode may have multiple arms and triggers.
Another is that continuous mode can be configured to start at any type of
trigger event, while overlap block mode must be in auto-trigger mode to act
like continuous mode. Finally, continuous mode always stops when a FIFO
overflow occurs, but overlap block mode does not.
HP E1433A User's Guide
Using the HP E1433A
3-31
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