
Chapter 4 516 Devices and DAQCard-500/700 Devices
DAQ Hardware Overview Guide 4-4 www.ni.com
516 Devices and DAQCard-500/700 Interval
Counter/Timer Operation
This section describes the operation of the 516 devices and the
DAQCard-500/700 interval counter/timer operation.
DAQCard-700 Counter/Timers
The DAQCard-700 contains an onboard MSM82C54 Programmable
Interval Timer chip that has three independent 16-bit counter/timers.
NI-DAQ uses the three counter/timers from the 82C54 as follows:
• Counter 0 is used for data acquisition operations.
• Counter 1 is available for counting/timing operations.
• Counter 2 can be reserved for Track*/Hold manipulation for the
SCXI-1140, and is otherwise available for counting/timing operations.
Figure 4-1 shows the connections of the MSM82C54 Counter/Timer
signals to the DAQCard-700 I/O connector.
Figure 4-1.
DAQCard-700 Counter/Timer Signal Connections
The counter has a clock input, a gate input, and an output labeled CLK,
GATE, and OUT, respectively. The clock pin for counters 1 and 2 and the
gate and output pins for counters 1, 2, and 3 are available on the device I/O
I/O Connector
1 MHz
Source
OUT2
CLK2
GAT2
OUT0
GAT0
CLK0
OUT1
CLK1
GAT1
MSM82C54
Counter/Timer
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