Chapter 3 Signal Connections
© National Instruments Corporation 3-17 DAQCard-1200 User Manual
Port C Pin Connections
The signals assigned to port C depend on how the 82C55A is configured.
In mode 0 or no handshaking configuration, port C is configured as
two 4-bit I/O ports. In modes 1 and 2, or handshaking configuration, port C
is used for status and handshaking signals with zero, two, or three lines
available for general-purpose I/O. Table3-3 summarizes the port C signal
assignments for each configuration.
Note Table3-3 shows both the port C signal assignments and the terminology
correlation between different documentation sources. The 82C55A terminology
refers to the different 82C55A configurations as modes, whereas NI-DAQ and
LabVIEW documentation refers to them as handshaking and no handshaking.
These signal assignments are the same for all four 82C55A PPIs.
Table 3-3. Port C Signal Assignments
Configuration Terminology Signal Assignments
82C55A/
DAQCard-1200
User Manual NI-DAQ/
LabVIEW PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0
Mode 0
(Basic I/O) No
Handshaking I/O I/O I/O I/O I/O I/O I/O I/O
Mode 1
(Strobed Input) Handshaking I/O I/O IBFASTBA*INTRASTBB* IBFBBINTRB
Mode 1
(Strobed Output) Handshaking OBFA*ACKA*I/O I/O INTRAACKB*OBFB*INTRB
Mode 2
(Bidirectional Bus) Handshaking OBFA*ACKA*IBFASTBA*INTRAI/O I/O I/O
*Indicates that the signal is active low.
Subscripts A and B denote port A or port B handshaking signals.