Programming instructions

© National Instruments Corporation 23-1 LabVIEW Data Acquisition Basics Manual
23
Things You Should Know
about Counters
Counters add counting or high-precision timing to your data acquisition
(DAQ) system. Counters respond to and output Transistor-Transistor Logic
(TTL) signals—square-pulse signals that are 0V (low) or 5V (high) in
value. The following diagram shows a TTL signal.
Even though counters just count the signal transitions (edges) of a
TTL source signal, you can use this counting capability in many ways.
• You can generate square TTL pulses for clock signals and triggers for
other DAQ applications.
• You can measure the pulse width of TTL signals.
• You can measure the frequency and period of TTL signals.
• You can count TTL signal transitions (edges) or elapsed time.
• You can divide the frequency of TTL signals.
The counter chapters that follow this chapter describe each of these counter
functions.
Signal Transitions
or Edges
+5 V
0 V