5-4 Remote Operation
Boolean parameters can have one
of
two values, usually ON
or
OFF. Boolean values
can also
he
represented by "1" or "0" on the command line. Queries requesting aBoolean
value will always retUfn either "1" or a "0".
A SCPI convention shows parameters in text and on the Command Tree with angle
brackets
«»
if
they are values
or
names to be entered by the user. Parameters with a
character (discrete) keyword
or
Boolean parameters
do
not use the angle brackets. A
Wavetek convention shows parameters in the command tree enclosed within an oval
"box". The default parameters that are selected at power-up
or
*RST
are shown in
shaded oval "boxes".
5.2.2 Queries
Any command that sets a value, can be queried about the current value
of
the setting.
The query form
of
the command ends with a question mark (?). Sorne commands are
defined as queries only and can be identified by the question mark used after them in
the command tree. Sorne commands are events only and do not have a query form.
These can usually
he
identified by their action nature such as DELete
or
IMMediate.
The values
of
the special numbers
of
MAXimum, MINimum, and DEFault may also
be queried.
5.2.3 SCPI Punctuation and Syntax
Keywords can be abbreviated or used in full. SCPI requires the exact abbreviation or
the exact full spelling only; capital
or
lower case letters have equal weight. The long
form
of
the keyword may
he
either a single word or a phrase which has been abbreviated
to a single word. The SCPI convention is to use the entire
keyword
in
any text or
instructions
with
the accepted abbreviation shown
in
capitalletters.
In
addition,
Wavetek makes the capital portion
bold
to show the minimum command requirements
at a glance, and sets
it
offby using a different typeface.
For
example,
FREQuency
Common commands must start with an asterisk (*). SCPI commands start with an
optional colon (:). Each time a colon is inserted in the command line, the "pointer" is
instrncted to move down the branch which has the keyword immediately following. A
semicolon (;) separates a string
of
commands on one tine.
If
a colon does not
fol1ow
the
semicolon, the "pointer" remains at the same level. A colon following the semicolon
will
set
the "pointer"
back
to the root.
The
commands
do
not
become
effective until a
"ProgramMessage Terrninator" is received at the end
of
the command line. An incorrect
command line will generate an error message.
5.2.4 Condensed Rules:
•Power-on
and
Reset
After
power
is applied, the
command
"pointer" is
set
to
the root and
all pararneters to default values (
*RST
does not set
the
Trace memory
to default values). .
.Command
line termination
When the
command
line is terminated
with
a
Program
Message
Terminator, the "pointer" is set to the
root
level.
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