Glossary
© National Instruments Corporation G-7 NI-488.2 User Manual for Windows
Ss Seconds.
SDC Selected Device Clear. The GPIB command used to reset internal or device
functions of an addressed Listener. See DCL.
semaphore An object that maintains a count between zero and some maximum value,
limiting the number of threads that are simultaneously accessing a shared
resource.
serial poll The process of polling and reading the status byte of one device at a time.
See parallel poll.
service request See SRQ.
source handshake The GPIB interface function that transmits data and commands. Talkers use
this function to send data, and the Controller uses it to send commands.
See acceptor handshake and handshake.
SPD Serial Poll Disable. The GPIB command used to cancel an SPE command.
SPE Serial Poll Enable. The GPIB command used to enable a specific device to
be polled. That device must also be addressed to talk. See SPD.
SRQ Service Request. The GPIB line that a device asserts to notify the CIC that
the device needs servicing.
status byte The IEEE 488.2-defined data byte sent by a device when it is serially
polled.
status word See ibsta.
synchronous Refers to the relationship between the GPIB driver functions and a process
when executing driver functions is predictable; the process is blocked until
the driver completes the function.
System Controller The single designated Controller that can assert control (become CIC of the
GPIB) by sending the Interface Clear (IFC) message. Other devices can
become CIC only by having control passed to them.