Chapter 5 295
Programming Fundamentals
SCPI Language Basics
Programming Fundamentals
proper SCPI terminator and separator when this is the case. There is
no current SCPI standard for RS-232. Although one intent of SCPI is to
be interface independent, <END> is only defined for IEEE 488
operation. At the time of this writing, the RS-232 terminator issue was
in the process of being addressed in IEEE standard 1174.
A semicolon (;) is not a SCPI terminator, it is a separator. The purpose
of the separator is to queue multiple commands or queries in order to
obtain multiple actions and/or responses. Make sure that you do not
attempt to use the semicolon as a terminator when using RS-232
control.
All binary trace and response data is terminated with <NL><END>, as
defined in Section 8.5 of IEEE Standard 488.2-1992, IEEE Standard
Codes, Formats, Protocols and Common Commands for Use with
ANSI/IEEE Std 488.1-1987. New York, NY, 1992.
The following are some examples of good and bad commands. The
examples are created from a theoretical instrument with the simple set
of commands indicated below:
[:SENSe]
:POWer
[:RF]
:ATTenuation 40dB
:TRIGger
[:SEQuence]
:EXTernal [1]
:SLOPe
POSitive
[:SENSe]
:FREQuency
:STARt
:POWer
[:RF]
:MIXer
:RANGe
[:UPPer]
Bad Command Good Command
PWR:ATT 40dB POW:ATT 40dB
The short form of POWER is POW, not PWR.
FREQ:STAR 30MHz;MIX:RANG
-20dBm
FREQ:STAR
30MHz;POW:MIX:RANG -20dBm
The MIX:RANG command is in the same :SENSE subsystem as FREQ, but
executing the FREQ command puts you back at the SENSE level. You must
specify POW to get to the MIX:RANG command.
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