Chapter 4
Signal Connections
©
National Instruments Corporation
4-3
DAQCard-DIO-24 User Manual
Signal Connection Descriptions
The absolute maximum voltage input rating is –0.5 to +5.5 V with
respect to GND.
Port C Pin Assignments
The signals assigned to port C depend on how you configure
the 82C55A. In mode 0, or no-handshaking mode, port C is configured
as two 4-bit I/O ports. If you configure port B for handshaking, lines
PC<0..2> are used as port B handshaking control lines. If you configure
port A for handshaking, some or all of lines PC<3..7> are used as port A
handshaking control lines, depending on the mode you select (mode 1
input, mode 1 output, or mode 2).
Table 4-1.
Signal Connection Descriptions
Pin
Signal Name
Description
1–8
PC<7..0>
Port C—Bidirectional data lines. PC7 is
the MSB, PC0 the LSB.
8–16
PB<7..0>
Port B—Bidirectional data lines. PB7 is
the MSB, PB0 the LSB.
17–24
PA<7..0>
Port A—Bidirectional data lines. PA7 is
the MSB, PA0 the LSB.
25
+5 V
+5 Volts—This pin pr5 VDC. The
+5 V supply is fused at 1.0 A, which is the
maximum current available.
26
SHIELD
Shield—This pin is connected to the card's
shield.
27
GND
Ground—This signal is connected to the
computer ground signal.
