Keithley 7001 User Manual

IEEE-488 Bus Overview
D-6
dress and are used to address devices to listen. The
actual command byte is obtained by ORing the prima-
ry address with $20.
TAG (Talk Address Group) — The talk commands are
derived from the primary address by ORing the ad-
dress with $40. Talk commands are used to address de-
vices to talk.
SCG (Secondary Command Group) — Commands in
this group provide additional addressing capabilities.
Many devices (including the Model 7001) do not use
these commands.
Unaddress commands
The two unaddress commands are used by the control-
ler to remove any talkers or listeners from the bus. ATN
is true when these commands are asserted.
UNL (Unlisten) — Listeners are placed in the listener
idle state by the UNL command.
UNT (Untalk) — Any previously commanded talkers
will be placed in the talker idle state by the UNT com-
mand.
Common commands
Common commands are commands that are common
to all devices on the bus. These commands are desig-
nated and defined by the IEEE-488.2 standard.
Generally, these commands are sent as one or more
ASCII characters that tell the device to perform a com-
mon operation, such as reset. The IEEE-488 bus treats
these commands as data in that ATN is false when the
commands are transmitted.
SCPI commands
SCPI commands are commands that are particular to
each device on the bus. These commands are designat-
ed by the instrument manufacturer, and are based on
the instrument model defined by the Standard Com-
mands for Programmable Instruments (SCPI) Consor-
tium’s SCPI standard.
Generally, these commands are sent as one or more
ASCII characters that tell the device to perform a par-
ticular operation, such as setting a range or closing a re-
lay. The IEEE-488 bus treats these commands as data in
that ATN is false when the commands are transmitted.
Command codes
Command codes for the various commands that use
the data lines are summarized in Figure D-3. Hexadec-
imal and the decimal values for the various commands
are listed in Table D-2.
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Keithley 7001 Specifications

General

Brand	Keithley
Model	7001
Category	Switch
Language	English