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Single command messages
The above command structure has three levels. The first level is made up of the root command
(:STATus) and serves as a path. The second level is made up of another path (:OPERation) and
a command (:PRESet). The third path is made up of one command for the :OPERation path. The
three commands in this structure can be executed by sending three separate program messages
as follows:
:stat:oper:enab <NRf>
:stat:oper:enab?
:stat:pres
In each of the above program messages, the path pointer starts at the root command (:stat)
and moves down the command levels until the command is executed.
Multiple command messages
You can send multiple command messages in the same program message as long as they are
separated by semicolons (;). The following is an example showing two commands in one
program message:
:stat:oper; :stat:oper:enab <NRf>
When the above is sent, the first command word is recognized as the root command (:stat).
When the next colon is detected, the path pointer moves down to the next command level and
executes the command. When the path pointer sees the colon after the semicolon (;), it resets
back to the root level and starts over.
Commands that are on the same command level can be executed without having to retype the
entire command path. Example:
:stat:oper:enab <NRf>; enab?
After the first command (:enab) is executed, the path pointer is at the third command level in
the structure. Since :enab? is also on the third level, it can be entered without repeating the entire
path name. Notice that the leading colon for :enab? is not included in the program message. If a
colon were included, the path pointer would reset to the root level and expect a root command.
Since :enab? is not a root command, an error would occur.
Command path rules
•
Each new program message must begin with the root command, unless it is optional
(e.g., [:SENSe]). If the root is optional, simply treat a command word on the next level
as the root.
•
The colon (:) at the beginning of a program message is optional and need not be used.
:stat:pres = stat:pres
•
When the path pointer detects a colon (:), it moves down to the next command level. An
exception is when the path pointer detects a semicolon (;), which is used to separate
commands within the program message.
•
When the path pointer detects a colon (:) that immediately follows a semicolon (;), it
resets back to the root level.
•
The path pointer can only move down. It cannot be moved up a level. Executing a
command at a higher level requires that you start over at the root command.
Remote Operation
11-25
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