Agilent Technologies N6751A User Manual page 69

Moving Among Subsystems
OUTPut:PROTection:CLEar (@1);:STATe:OPERation:CONDition? (@1)
VOLTage:LEVel 7.5,(@1);PROTection 10,(@1);:CURRent:LEVel 0.5,(@1)
Including Common Commands
Using Queries
Series N6700 User's Guide
defined as "OUTPut" and thus the instrument interpreted the second
command as:
OUTPut:PROTection:CLEar (@1)
In fact, it would have been syntactically incorrect to include the
"OUTP" explicitly in the second command, since the result after
combining it with the header path would be:
OUTPut:OUTPut:PROTection:CLEar (@1)
which is incorrect.
In order to combine commands from different subsystems, you need
to be able to reset the header path to a null string within a message.
You do this by beginning the command with a colon (:), which
discards any previous header path. For example, you could clear the
output protection and check the status of the Operation Condition
register in one message by using a root specifier as follows:
The following message shows how to combine commands from
different subsystems as well as within the same subsystem:
Note the use of the optional header LEVel to maintain the correct
path within the subsystems, and the use of the root specifier to move
between subsystems.
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 header path; you may insert them
anywhere in the message.
OUTPut OFF,(@1);*RCL 1;OUTPut ON,(@1)
Observe the following precautions with queries:
Add a blank space between the query indicator (?) and any
subsequent parameter such as a channel list.
Allocate the proper number of variables for the returned data.
Read back all the results of a query before sending another
command to the power system. Otherwise, a Query Interrupted
error will occur and the unreturned data will be lost.
Introduction to Programming 5
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