Structure and Syntax of Device Messages CMU
1100.4903.12 5.10 E-8
Example: CALL IBWRT(device%, "TRIG:
SOUR EXT ")
CALL IBWRT(device%, "TRIG:
THR LOW ")
Responses to Queries
A query is defined for each setting command unless explicitly specified otherwise. It is formed by add-
ing a question mark to the associated setting command. According to SCPI, the responses to queries
are partly subject to stricter rules than in standard IEEE 488.2.
1. The requested parameter is transmitted without header.
Example: TRIGger:THReshold? Response: LOW
2. Maximum values, minimum values and all further quantities, which are requested via a special text
parameter are returned as numerical values
Example: CONFigure:POWer:CONTrol:REPetition? MAX Response: 10000
3. Numerical values are output without a unit. Physical quantities are referred to the basic units or to
the units set using the Unit command.
Example: SENSe:SPECtrum:FREQuency:STARt? Response: 1E6 for 1 MHz
4. Boolean values are returned as 0 (for OFF) and 1 (for ON).
Example: SOURce:DM:CLOCk:STATe? Response: 1
5. Text (character data) is returned in a short form (see also next section).
Example: FETCh:SPECtrum:STATus? Response: ERR
Parameters
Most commands require a parameter to be specified. The parameters must be separated from the
header by a "white space". Permissible parameters are numerical values, Boolean parameters, text,
character strings and block data. The type of parameter required for the respective command and the
permissible range of values are specified in the command description.
Numerical values Numerical values can be entered in any form, i.e. with sign, decimal point and
exponent. Values exceeding the resolution of the instrument are rounded up or
down. The mantissa may comprise up to 255 characters, the values must be in
the value range –9.9E37 to 9.9E37. The exponent is introduced by an "E" or
"e". Entry of the exponent alone is not allowed. In the case of physical quanti-
ties, the unit can be entered. Permissible unit prefixes are G (giga), MA
(mega), MOHM and MHZ are also permissible), K (kilo), M (milli), U (micro)
and N (nano). If the unit is missing, the basic unit is used.
Example: SENS:SPEC:FREQ:STOP 1.5GHz is equivalent to
SENS:SPEC:FREQ:STOP 1.5E9
Special numerical The texts MINimum, MAXimum, DEFault, UP and DOWN are interpreted as
values special numerical values.
In the case of a query, the associated numerical value is provided.
Example: Setting command: CONF:POW:CONT:REP MAXimum
Query: CONF:POW:CONT:REP?
Response: 100
MIN/MAX MINimum and MAXimum denote the minimum and maximum value.
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