Chapter 2 Using Your 653X
653X User Manual 2-30 ni.com
Figure 2-19. Pattern-Detection Trigger Example
Tip To prevent a transient data value during line switching from falsely causing a match,
set a valid pattern for at least 60ns to guarantee detection. In addition, keep glitches to less
than 20 ns to guarantee rejection.
Choosing Continuous or Finite Data Transfer
You can acquire data continuously into or from computer memory or
specify the number of points you want to transfer.
Finite Transfers
For finite transfers, the 653X device inputs the specified amount of data to
a computer memory buffer and stops the operation.
Continuous Input
For continuous input, the 653X device transfers input data to the computer
memory buffer continuously. As the device is filling the buffer, call the
DIG_DB_Transfer function or the DIO Read VI to retrieve the data. If at
any time the device runs out of space in the buffer, it stops the operation
and NI-DAQ returns an error.
You have the option to allow the device to continue when it runs out of
buffer space and overwrite data you have not yet read. You can specify this
through the oldDataStop parameter in the DIG_DB_Config function and
the Data Overwrite/Regenerate parameter in the Digital Buffer Control VI,
called by the DIO Start VI.
XXXXXX10
00000010
00000011
Postive: Search for Match
Value to Detect
Pattern
Mask
Polarity