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Easy I/O for DAQ Library Chapter 10
LabWindows/CVI Standard Libraries 10-56 © National Instruments Corporation
Return Value
error
short integer Refer to error codes in Table 10-5.
Parameter Discussion
portNumber specifies the digital port this function configures.
A portNumber value of 0 signifies port 0, a portNumber of 1 signifies port 1, and so on. If you
use an SCXI-1160, SCXI-1161, SCXI-1162, or SCXI-1163 module, use the
"SCx!MDy!0"
syntax, where
x
is the chassis ID and
y
is the module device number, to specify the port on a
module.
portWidth is the total width in bits of the port. For example, you can combine two 4-bit ports
into an 8-bit port on an MIO (non E-Series) board by setting portWidth to 8.
• When portWidth is greater than the physical port width of a digital port, the following
restrictions apply. The portWidth must be an integral multiple of the physical port width,
and the port numbers in the combined port must begin with the port named by portNumber
and must increase consecutively. For example, if portNumber is 3 and portWidth is
24(bits), LabWindows/CVI uses ports 3, 4, and 5.
• The portWidth for the 8255-based digital I/O ports (including all digital ports on Lab
boards, SCXI-1200, DAQPad-1200, DAQCard-1200, DIO-24, DIO-32F, DIO-96, and
AT-MIO-16DE-10/AT-MIO-16D ports 2, 3 and 4) should be at least 8.
configure specifies whether to configure the digital port before writing.
• When this function is called in a loop, it can be optimized by only configuring the digital port
on the first iteration.
• When you configure a digital I/O port that is part of an 8255 PPI (including all digital ports
on Lab boards, SCXI-1200, DAQPad-1200, DAQCard-1200, DIO-24, DIO-32F, DIO-96,
and AT-MIO-16DE-10/AT-MIO-16D ports 2, 3 and 4), the 8255 PPI goes through a
configuration phase, where all the ports within the same PPI chip get reset to logic low,
regardless of the data direction. The data directions on other ports, however, are maintained.