Timing specifications, Table 3-2. port c signal assignments, Table 3-2 – National Instruments Low-Cost Multifunction I/O Board for ISA Lab-PC+ User Manual
Page 47: Port c signal assignments
Signal Connections
Chapter 3
Lab-PC+ User Manual
3-16
© National Instruments Corporation
Table 3-2. Port C Signal Assignments
Programmable
Mode
Group A
Group B
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
Mode 0
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
Mode 1 Input
I/O
I/O
IBFA
STBA*
INTRA
STBB*
IBFBB
INTRB
Mode 1 Output
OBFA*
ACKA*
I/O
I/O
INTRA
ACKB*
OBFB*
INTRB
Mode 2
OBFA*
ACKA*
IBFA
STBA*
INTRA
I/O
I/O
I/O
*Indicates that the signal is active low.
Timing Specifications
The handshaking lines STB* and IBF are used to synchronize input transfers. The handshaking
lines OBF* and ACK* are used to synchronize output transfers.
The following signals are used in the timing diagrams shown later in this chapter:
Name
Type
Description
STB*
Input
Strobe input–A low signal on this handshaking line loads data into
the input latch.
IBF
Output
Input buffer full–A high signal on this handshaking line indicates
that data has been loaded into the input latch. This is primarily an
input acknowledge signal.
ACK*
Input
Acknowledge input–A low signal on this handshaking line
indicates that the data written from the specified port has been
accepted. This signal is primarily a response from the external
device that it has received the data from the Lab-PC+.