National Instruments PCI-6251 User Manual

© National Instruments | 6-7
M Series User Manual
DI Change Detection
You can configure the DAQ device to detect changes in the DIO signals. Figure 6-3 shows a
block diagram of the DIO change detection circuitry.
Figure 6-3. DI Change Detection
Note DI change detection is supported in NI-DAQmx 8.0 and later.
You can enable the DIO change detection circuitry to detect rising edges, falling edges, or either
edge individually on each DIO line. The DAQ devices synchronize each DI signal to
80MHzTimebase, and then sends the signal to the change detectors. The circuitry ORs the output
of all enabled change detectors from every DI signal. The result of this OR is the Change
Detection Event signal.
The Change Detection Event signal can do the following:
• Drive any RTSI <0..7>, PFI <0..15>, or PXI_STAR signal
• Drive the DO Sample Clock or DI Sample Clock
• Generate an interrupt
The Change Detection Event signal also can be used to detect changes on digital output events.
Synch
Synch
P0.0
P0.31
Enable
Enable
Enable
Enable
Change Detection Event

National Instruments PCI-6251 Specifications

General

Brand	National Instruments
Model	PCI-6251
Category	I/O Systems
Language	English