Chapter 2
Using Your NI 653X
©
National Instruments Corporation
2-17
Note
Because output data is preloaded to the NI 6534 buffer, you cannot use DAQEvents
(called Progress events in the CWDO object of Measurement Studio) to monitor the
progress of pattern generation. A DAQEvent is fired when data is preloaded into the
NI 6534 onboard memory from the PC memory, so the event indicates a data transfer from
the PC memory,
not
the progress of pattern generation from the NI 6534 to an external
device.
Transferring Data Between Two
Devices—Handshaking I/O
If you want to communicate with an external device using an exchange of
signals to request and acknowledge each data transfer, use the handshaking
I/O mode.
Choosing the Width of Data to Transfer
You can choose between a width of 8, 16, or 32 bits. Use the following
table to find the valid combinations of ports and timing controllers you can
use based on the width of data you want to transfer.
Deciding Data Transfer Direction
You can choose to send data from the NI 653
X
to the peripheral device
(output) or from the peripheral device to the NI 653
X
(input).
Deciding Which Handshaking Protocol to Use
The NI 653
X
supports several different handshaking protocols to
communicate with your peripheral device. The protocol you select
determines the timing of the ACK and REQ signals.
Table 2-3.
Port and Timing Controller Combinations
Transfer
Width
Possible Port
Combinations
Timing Controllers
That Can Be Used
8 bits
Port 0 (DIOA<0..7>)
Group 1
Port 2 (DIOC<0..7>)
Group 2
16 bits
Port 0, Port 1
Group 1
Port 2, Port 3
Group 2
32 bits
Port 0, Port 1, Port 2, Port 3
Group 1
Содержание NI 653 Series
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