User Manual
CHAPTER 1. INTRODUCTION TO SCPI 2
1.2.3 Multiple Commands in a Message
Multiple SCPI commands can be combined and sent as a single message. There are two important conditions when
sending several commands within a single message:
• Use a semicolon to separate commands within a message.
• There is an implied header path that aects how commands are interpreted by the electronic load.
The header path can be thought of as a string that gets inserted before each command within a message. For the
first command in a message, the header path is a null string. For each subsequent command the header path is
defined as the characters that make up the headers of the previous command in the message up to and including
the last colon separator. An example of a message with two commands:
“CURR:LEV 3;PROT:STAT OFF ”.
This shows the use of the semicolon separating the two commands, and also illustrates the header path concept. The
leading header “CURR” of the second command was omied because aer the "CURR:LEV 3" command, the header
path is defined as "CURR". It is syntactically incorrect to include the "CURR" explicitly in the second command,
since the result aer combining it with the header path would be “CURR:CURR:PROT:STAT OFF”, a nonexistent
command.
1.2.4 Moving Among Subsystems
In order to combine commands from dierent subsystems, a reset of the header path is needed. Adding a preceding
colon (:) accomplishes this. For example, clearing the output protection and checking the Operation Condition
register in one message as follows:
PROTection:CLEAr; :STATus:OPERation:CONDition?
Commands from dierent subsystems may be combined as well as those of the same subsystem:
POWer:LEVel 200;PROTection 28;:CURRent:LEVel 3;PROTection:STATe ON
The optional header LEVel maintains the correct path within the voltage and current subsystems. The use of the
root specifier signals a move between subsystems.
Common commands do not aect the header path, and may be inserted anywhere in a message.
VOLTage 17.5;*TRG
OUTPut OFF;*RCL 2;OUTPut ON
1.2.5 Case Sensitivity
Common commands and SCPI commands are not case sensitive. You can use upper or lower case and any case
combination.
Example:
*RST = *rst
:DATA? = :data?
:SYSTem:PRESet = :system:preset