Chapter 4 Hardware Overview
© National Instruments Corporation 4-15 NI 5102 User Manual
Analog Trigger Circuit
The NI 5102 contains a sophisticated analog trigger circuit that accepts
boolean outputs from level comparators and makes intelligent decisions
about the trigger. Several triggering modes are available, including edge,
window, and hysteresis. For information on configuring trigger functions,
see the Triggering Functions and Parameters section in Chapter 3,
Common Functions and Examples, of your NI-SCOPE Software User
Manual.
Trigger Hold-off
Trigger hold-off is the length of time that the NI 5102 waits after finishing
an acquisition before it may accept another trigger. Hold-off is provided in
hardware using a 24-bit down counter clocked by a 2.5 MHz internal
timebase. With thisconfiguration, you can selecta hardware hold-off value
of 800 ns to 6.71 s in increments of 400 ns.
When anacquisition isin progress, the counteris loaded witha digital value
that corresponds tothe desired hold-offtime. TheEnd of Acquisition signal
triggers the counter to start counting down. Before the counter reaches its
terminal count (TC), all triggers are rejected in hardware. At TC, the
hold-off counter reloads the hold-off value and prepares to accept the next
trigger. Figure 4-11 shows a timing diagram of signals when hold-off is
enabled.
