Chapter 2
Using Your NI 653X
©
National Instruments Corporation
2-29
Deciding Which Lines You Want to Monitor
You need to specify which of the lines in your acquisition you want to
monitor for changes.
Specify which bits are significant to you by using a software line mask in
the
DIG_Trigger_Config
function in NI-DAQ C interface, and the
Digital Trigger Config VI for LabVIEW. In the following example, the user
specifies the mask to detect changes on the two least-significant bits of a
port. Pattern 1 does not have changes in the two bits of interest, and data is
not latched. For pattern 2, however, a change is detected on one of the two
bits of interest, and the value of the entire port is acquired.
Figure 2-15.
Change Detection Example Settings
16 bits
Port 0, Port 1
Group 1
Port 2, Port 3
Group 2
32 bits
Port 0, Port 1, Port 2, Port 3
Group 1
Mask
0 0 0 0 0 0 1 1
Initial Input Pattern
0 0 0 0 0 0 1 0
Input Pattern 1
0 1 0 0 0 0 1 0
No change on specified bits.
Data is not latched.
Input Pattern 2
0 0 0 0 0 0 1 1
Change detected,
latch entire port.
Table 2-4.
Port and Timing Controller Combinations (Continued)
Transfer
Width
Possible Port
Combinations
Timing Controllers
That Can Be Used
