National Instruments 6023E User Manual
Page 56
Chapter 4
Signal Connections
4-26
ni.com
ACK*
Input
Acknowledge input—a low signal on this handshaking line
indicates that the data written to the port has been accepted. This
signal is a response from the external device indicating that it has
received the data from your DIO device.
OBF*
Output
Output buffer full—a low signal on this handshaking line indicates
that data has been written to the port.
INTR
Output
Interrupt request—this signal becomes high when the 82C55A
requests service during a data transfer. You must set the appropriate
interrupt enable bits to generate this signal.
RD*
Internal
Read—this signal is the read signal generated from the control lines
of the computer I/O expansion bus.
WR*
Internal
Write—this signal is the write signal generated from the control
lines of the computer I/O expansion bus.
DATA
Bidirectional
Data lines at the specified port—for output mode, this signal
indicates the availability of data on the data line. For input mode,
this signal indicates when the data on the data lines should be valid.
Table 4-5. Signal Names Used in Timing Diagrams (Continued)
Name
Type
Description