Logical Instruments; Time And Date Values - Keithley 708B Reference Manual

Models 707B and 708B Switching Matrix Reference Manual

Logical instruments

You would normally refer to all instrumentation in one enclosure or node as a single instrument. In the
context of TSP and instrument control libraries, it is useful to think of each individual subdivision in an
enclosure, such as a card slot or the channels, as a standalone instrument. To avoid confusion, all
subdivisions of the instrumentation in an enclosure are referred to as "logical instruments."
Each logical instrument is given a unique identifier in a system. These identifiers are used as part of
all ICL commands that control a given logical instrument. The logical instruments are:
•
beeper
•
bit
•
channel
•
digio
•
display
•
eventlog
•
errorqueue
•
format
•
gpib
•
lan
•
scan
•
slot
•
status
•
timer
•
trigger
•
tsplink
Do not create variable names that are the same as names of logical instruments. Doing so will result
in the loss of use of the logical instrument and its associated ICLs. For example, if you send the
command digio = 5, you cannot access the digio.* ICL commands until you cycle the power to
the instrument.

Time and date values

Time and date values are represented as the number of seconds since some base. Representing
time as a number of seconds is referred to as "standard time format." There are three time bases:
•
UTC 12:00 am Jan 1, 1970. Some examples of UTC time are reading buffer base timestamps,
adjustment dates, and the value returned by os.time().
•
Instrument on. References time to when the instrument was turned on. The value returned by
os.clock() is referenced to the turn-on time.
•
Event. Time referenced to an event, such as the first reading stored in a reading buffer.
707B-901-01 Rev. A / August 2010
NOTE
Section 7: Command reference
7-3