Timing Specifications; Table 3-3. Timing Signal Descriptions - National Instruments DAQPad-6508 User Manual

Chapter 3 Signal Connections

Timing Specifications

Name Type
STB* Input
IBF Output
ACK* Input
OBF* Output
INTR Output
RD* Internal
WR* Internal
DATA Bidirectional
DAQPad-6507/6508 User Manual
This section lists the timing specifications for handshaking with the
DAQPad-6507/6508 devices. The handshaking lines STB* and IBF
synchronize input transfers. The handshaking lines OBF* and ACK*
synchronize output transfers.
The signals in Table 3-3 are used in the timing diagrams later in this
chapter.

Table 3-3. Timing Signal Descriptions

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 an input
acknowledge signal.
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 the DAQPad-6507/6508 devices.
Output Buffer Full—A low signal on this handshaking line
indicates that data has been written to the port.
Interrupt Request—This signal becomes high when the 82C55A
requests service during a data transfer. The appropriate interrupt
enable bits must be set to generate this signal.
Read Signal—This signal is the read signal generated from the
control lines of the computer I/O expansion bus.
Write Signal—This signal is the write signal generated from the
control lines of the computer I/O expansion bus.
Data Lines at the Specified Port—This signal indicates the
availability of data on the data lines at a port that is in the output
mode. If the port is in the input mode, this signal indicates when the
data on the data lines should be valid.
Description
3-12 © National Instruments Corporation