Timing Specifications; Table 3-2. Port C Signal Assignments - National Instruments Low-Cost Multifunction I/O Board for ISA Lab-PC+ User Manual

Signal Connections
Programmable
Mode
Mode 0
Mode 1 Input
Mode 1 Output
Mode 2
*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
STB* Input
IBF Output
ACK* Input
Lab-PC+ User Manual

Table 3-2. Port C Signal Assignments

Group A
PC7 PC6 PC5
I/O I/O I/O
I/O I/O IBF A
OBF A * ACK A * I/O
OBF A * ACK A * IBF A
Description
Strobe input–A low signal on this handshaking line loads data into
the input latch.
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.
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+.
PC4 PC3
I/O I/O
STB A * INTR A
I/O INTR A
STB A * INTR A
3-16 © National Instruments Corporation
Chapter 3
Group B
PC2 PC1 PC0
I/O I/O I/O
STB B * IBFB B INTR B
ACK B * OBF B * INTR B
I/O I/O I/O