Deciding Transfer Direction; Choosing An Internal Or External Req Source; Reversing The Req Polarity - National Instruments NI 653 Series User Manual

Deciding Transfer Direction

Choosing an Internal or External REQ Source

Reversing the REQ Polarity

Note
For more information on LabVIEW VIs and NI-DAQ functions, consult the
LabVIEW Help and the NI-DAQ Function Reference Help.
© National Instruments Corporation
Table 2-2. Port and Timing Controller Combinations (Continued)
Transfer Possible Port
Width Combinations
16 bits Port 0, Port 1
Port 2, Port 3
32 bits Port 0, Port 1, Port 2, Port 3
You can choose to send data from your NI 653X to the peripheral device
(output) or from the peripheral device to your NI 653X (input).
In pattern I/O, the NI 653X acquires/generates data on every falling or
rising edge (programmable) of the REQ signal. The REQ signal can be
generated internally or based on the clock of a peripheral device. An
example of using external REQ is sharing a sample clock of an analog input
device so you can synchronize the analog and digital operations.
By default, data from an external REQ source is transferred on the rising
edge of the signal and on the falling edge of the internal REQ source. You
can reverse the REQ polarity by using the following functions:
• NI-DAQ C interface—Specify the REQ polarity in
before calling
DIG_Block_PG_Config
• LabVIEW—Specify the REQ polarity with the request polarity
parameter in the Digital Mode Config VI, which is called by
DIO Config VI.
Refer to Table C-1, NI 653X I/O Connector 68-Pin
overview of all control/timing trigger lines.
2-7
Chapter 2 Using Your NI 653X
Timing Controllers
That Can Be Used
Group 1
Group 2
Group 1
DIG_Group_Mode
.
Assignments, for an
NI 653X User Manual