Programming instructions

Chapter 23 Things You Should Know about Counters
© National Instruments Corporation 23-3 LabVIEW Data Acquisition Basics Manual
outputs, then you should use a toggled output. Refer to Chapter 24,
Generating a Square Pulse or Pulse Trains,
for more information.
Multiple counters can be concatenated for a greater counting range on most
devices. For more information on how to concatenate counters, refer to
Chapter 27,
Counting Signal Highs and Lows
.
Knowing Your Counter Chip
Most National Instruments DAQ devices contain one of three different
counter chips: the DAQ-STC, the Am9513, or the 8253/54 chip. Typically,
E-series boards (for example the AT-MIO-16E-1) use the DAQ-STC chip,
legacy-type MIO boards (for example the AT-MIO-16) use the Am9513
chip, and low cost Lab/1200 type boards (for example the Lab-PC-1200)
use the 8253/54 chip. If you are not sure which chip your device uses, refer
to your hardware manual.
Figure 23-1.
Counter Gating Modes
1
GATE
Counter Value
2
SOURCE
4
3
5
7
6
8
count rising SOURCE edge
Falling Edge Gating
1
GATE
Counter Value
2
SOURCE
4
3
5
7
6
8
10
9
count rising SOURCE edge
Rising Edge Gating
1
GATE
Counter Value
2
SOURCE
4
3
5
6
count rising SOURCE edge
High-Level Gating
1
GATE
Counter Value
2
SOURCE
4
3
5
6
count rising SOURCE edge
Low-Level Gating