National Instruments DIO 6533 사용자 설명서
Chapter 5
Signal Timing
DIO 6533 User Manual
5-4
© National Instruments Corporation
respectively. Using only a start trigger, you can do posttrigger data
acquisition. A stop trigger enables you to do pretrigger data acquisition,
or combined pretrigger and posttrigger data acquisition. After detecting
the stop trigger, the 6533 device begins counting the post-stop-trigger
portion of the data acquisition. Figure 5-4 shows trigger pulse timing,
where t
acquisition. A stop trigger enables you to do pretrigger data acquisition,
or combined pretrigger and posttrigger data acquisition. After detecting
the stop trigger, the 6533 device begins counting the post-stop-trigger
portion of the data acquisition. Figure 5-4 shows trigger pulse timing,
where t
w
is pulse width.
Figure 5-4. Trigger Input Signal Timing
Instead of a pulse on the I/O connector, you can also use digital pattern
detection as a trigger to start or stop an input operation. See Chapter 3,
detection as a trigger to start or stop an input operation. See Chapter 3,
, for more information about pattern detection.
Handshake Timing
This section describes the 6533 device two-way handshaking modes
and the timing specifications of each mode.
and the timing specifications of each mode.
In handshaking, the ACK signal always conveys information about
when the 6533 device is ready for a transfer. The REQ signal conveys
information about when the peripheral device is ready for a transfer.
when the 6533 device is ready for a transfer. The REQ signal conveys
information about when the peripheral device is ready for a transfer.
Note: Depending on the protocol and the direction of the transfer, either an ACK
or a REQ signal can occur first in the handshaking sequence.
8255 Emulation
The 8255 emulation mode handshakes in a manner compatible with an
8255 or 82C55 Programmable Peripheral Interface (PPI). The 8255 and
82C55 PPIs are digital I/O chips used on many digital DAQ devices,
such as the National Instruments PC-DIO-24 and PC-DIO-96/PnP.
8255 or 82C55 Programmable Peripheral Interface (PPI). The 8255 and
82C55 PPIs are digital I/O chips used on many digital DAQ devices,
such as the National Instruments PC-DIO-24 and PC-DIO-96/PnP.
Rising-Edge
Polarity
Falling-Edge
Polarity
t w
t w = 10 ns minimum