National Instruments 6023E, 6024E, 6025E - page 56

Chapter4 SignalConnections
6023E/6024E/6025EUser Manual 4-26 ni.com
ACK* Input Acknowledge input—a low signal on this handshaking line
indicatesthat the data written to the port has been accepted. This
signalis aresponse from the external device indicating that it has
receivedthe data from your DIO device.
OBF* Output Output bufferfull—a low signal on this handshaking line indicates
that data has been written to the port.
INTR Output Interrupt request—this signalb ecomes high when the 82C55A
requestsservice during a data transfer. Youmu st set the appropriate
interrupt enable bits to generate this signal.
RD* Internal Read—thissignal is the read signal generated from the control lines
of the computer I/O expansion bus.
WR* Internal Write—thissi gnal is the write signal generated from the control
lines of the computer I/O expansion bus.
DATA Bidirectional Datalines at the specified port—for output mode, this signal
indicates the availabilityof data on the data line. For input mode,
thissignal indicates when the data on the data lines should be valid.
Table4-5. Signal Names Used in Timing Diagrams (Continued)
Name Type Description