© National Instruments Corporation 9 NI 6528/6529 User Guide and Specifications
The filter clock is programmable and allows you to control how long a
pulse must last to be recognized. The sample clock provides a fast sample
rate to ensure that input pulses remain constant between filter clocks.
Digital Filtering Example
Figure 3 shows a filter configuration with a t
interval
filter interval
(t
interval
/2 filter clock).
Figure 3. Digital Filtering Example
In periods A and B, the filter blocks the glitches because the external signal
does not remain steadily high from one rising edge of the filter clock to the
next. In period C, the filter passes the transition because the external signal
remains steadily high. Depending on when the transition occurs, the filter
may require up to two filter clocks—one full filter interval—to pass a
transition. The figure shows a rising (0 to 1) transition. The same filtering
applies to falling (1 to 0) transitions.
RTSI
The NI 6528/6529 uses the National Instruments Real-Time System
Integration (RTSI) bus interface to route additional timing and trigger
signals between the NI 6528/6529 and National Instruments
RTSI-compatible devices. Use the National Instruments RTSI cable to
connect the NI PCI-6528 to other RTSI-compatible devices.
The NI PXI-6528/6529 uses pins on the RTSI connector to connect the
RTSI bus to the PXI trigger bus, as defined in the PXI Hardware
Specification, Revision 2.1. The NI PCI-6528 uses pins on the RTSI
connector to connect the RTSI bus to the PCI trigger bus, as defined in the
PCI Local Bus Specification, Revision 2.2. All National Instruments
PCI/PXI devices that have a connection to these pins can be connected
through software. This feature is not supported by CompactPCI.
HHHHH
HLLHH
HLLHH
A
B
C
Sample Clock
External
Signal
Sampled
Filtered
Signal
External
Signal
Filter
Clock
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