National Instruments DIO 6533 - Manual (Page 60)

© National Instruments Corporation 5-1 DIO 6533 User Manual
Chapter
5
Signal Timing
This chapter provides detailed timing specifications for DIO 6533
pattern generation and for the various full, two-way handshaking
modes.
Pattern-Generation Timing
Pattern-generation timing is similar for digital data acquisition (input)
and digital waveform generation (output). Data transfers are timed by
request pulses, carried on the REQ pin. The 6533 devices can generate
request pulses internally, or you can provide external pulses. Each
request pulse strobes a data point into or out of the 6533 device.
You can use up to two additional timing signals, if you select triggered
pattern generation: a start trigger and a stop trigger. A start trigger, if
used, begins the pattern-generation operation. A stop trigger ends the
operation. However, you can specify a number of data points to transfer
after the stop trigger.
You can substitute a digital pattern for either the start or stop trigger. In
this case, the operation begins or ends when the 6533 device detects a
particular digital pattern on the data lines belonging to the group.
Figure 5-1 shows a pattern-generation operation using request pulses, a
start trigger, and a stop trigger.
Figure 5-1. Pattern-Generation Timing
REQ
STOPTRIG
ACK (STARTTRIG)
Pretrigger Data Posttrigger Data