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Chapter 2 Function Reference — DIG_Block_PG_Config
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National Instruments Corporation 2-155 NI-DAQ FRM for PC Compatibles
2: Change detection (DIO 6533 (DIO-32HS) input groups only). The board
generates an internal request whenever it detects a change on a significant input
pin.
When using internally generated requests (reqSource 0 or 2), the REQ signal is an output;
do not drive any external signal onto the REQ pin of the I/O connector.
NI-DAQ considers all of the group’s lines significant for change detection by default.
However, you can set a mask specifying that only certain lines should be compared. The
same lines that are significant for pattern detection, if used, are also significant for change
detection. If you are using pattern-detection messaging (DAQEvent 7 or 8), use the
DAQTrigVal0 parameter of the
Config_DAQ_Event_Message function to set the
pattern-and-change-detection mask. Otherwise, use the line-mask parameter of the
DIG_Trigger_Config function. When using the DIG_Trigger_Config function to set a
line mask, you do not need to select any particular start trigger, stop trigger, or search pattern.
timebase determines the amount of time that elapses during a single reqInterval. The
following values are possible for timebase:
–3: 50 ns (DIO 6533 [DIO-32HS] only).
1: 1 µs.
2: 10 µs.
3: 100 µs.
4: 1 ms.
5: 10 ms.
reqInterval is a count of the number of timebase units of time that elapses between internally
produced request signals.
Range: 2 through 65,535.
externalGate is an absolute parameter and should be set to 0. The AT-DIO-32F does support
external gating but this simply requires making a connection at the I/O connector. If you use
external gating for group 1, the signal connected to IN1 gates the pattern. If you use external
gating for group 2, the signal connected to IN2 gates the pattern. For an AT-DIO-32F, the
signal at INx must be high to enable the pattern. The DIO 6533 (DIO-32HS) devices use
triggering instead of gating; for more information, refer to the
DIG_Trigger_Config
function.
Using This Function
DIG_Block_PG_Config enables or disables the pattern generation mode of digital I/O. If the
config parameter equals 1 or 2, any subsequent
DIG_Block_In or DIG_Block_Out call
initiates a pattern generation operation. Pattern generation differs from handshaking I/O in
that NI-DAQ produces the request signals at regularly clocked intervals. If reqSource equals
0, the timebase parameter equals 2, and the reqInterval parameter equals 10, NI-DAQ reads
a new pattern from or writes a pattern to a group every 100 µs.