Counting Signal Edges (Buffered)

Description

It may be necessary for a particular application to repeatedly count events in response to some hardware signal, or to synchronize the counting with another acquisition. In this case, it is necessary to use buffered event counting.

Buffered event counting counts all events on the source pin, but only latches data into the buffer on the edge of a gate pulse. Unlike regular event counting, where the gate controls if the counter is counting and the software controls when the counter is read, buffered counting uses the gate to time when the counter is read, so that the data is never subject to software latencies. The method of buffering may be either a single buffer, in which case the user must specify the number of counts to count, after which point the counter will stop counting, or double buffering may be used instead, which allows continuous counting until the software tells the counter to stop.

Common Applications

Buffered counting is only available with the DAQ-STC and NI-TIO based counters (E-series and PCI-660x, respectively). Continuous buffered counting is only available with NI-DAQ 6.5.0 and later.

Reader Comments | Submit a comment »

More PCI cards have STC than those listed
The article implies that buffered counting can only be used for E-series and PCI-660x since only those card series have STC or TIO based counters. I am pretty sure that at least most of the new M-series cards have STC based counters and thus also could be used with buffered counting. References: http://sine.ni.com/nips/cds/view/p/lang/en/nid/201760 http://www.ni.com/dataacquisition/mseries.htm
- Alex Krause, CalTech. a19grey@bu.edu - Aug 11, 2008