RP Series
March 2011
45
If you now enter :VOLTage, the active path again moves one colon to the right. The interface
is now ready to accept either :RANGe or :LEVel as the next header.
If you now enter :RANGe you have reached the end of the command string. The active
header path remains at :RANGe If you wished, you could have entered :RANGe 136 ;LEVel
115 and it would be accepted as a compound message consisting of:
1. SOUR:VOLT:RANG 136.
2. SOUR:VOLT:LEV 115.
The entire message would be:
SOUR:VOLT:RANG 136;LEV 115.
The message terminator after LEVel 115 returns the path to the root.
Note:
The RP Series interface buffer is limited to 21 characters, however. As such,
compound commands are not recommended as they often exceed this message length limit.
Moving Among Subsystems
In order to combine commands from different subsystems, you need to be able to restore the
active path to the root. You do this with the root specifier (:). For example, you could set the
output frequency to 60 Hz and set the display mode to frequency.
FREQ 60
DISP:MODE 0
Because the root specifier resets the command parser to the root, you can use the root
specifier and do the same thing in one message:
FREQ 60;:DISP:MODE 0
Including Common Commands
You can combine common commands with system commands in the same message. Treat
the common command as a message unit by separating it with a semicolon (the message
unit separator). Common commands do not affect the active header path; you may insert
them anywhere in the message.
VOLTage 115;*ESE 255
OUTPut 0;*RCL 2
12.3. Using Queries
Observe the following precautions with queries:
Set up the proper number of variables for the returned data.
Read back all the results of a query before sending another command to the AC source.
Otherwise a Query Error will occur and the unreturned data will be lost.
