AMETEK Lx Series II Programming Manual - Manual (Page 17)

Programming Manual Lx \ Ls Series II
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2.2.3 The SCPI Command Tree
As previously explained, the basic SCPI communication method involves sending one or more
properly formatted commands from the SCPI command tree to the instrument as program
messages. Figure 2-1 shows a portion of a subsystem command tree, from which you access the
commands located along the various paths (you can see the complete tree in appendix A).
Root
:OUTPut
:COUPling
:DFI
:PROTection
:OPERation
:SOURce
:CLEar
:DELay
:STATus
[:STATe]
[:STATe]
[:EVEN]?
:CONDition?
Figure 2-1: Partial Command Tree
The Root Level
Note the location of the ROOT node at the top of the tree. Commands at the root level are at the
top level of the command tree. The SCPI interface is at this location when:
the AC source is powered on
a device clear (DCL) is sent to the AC source
the SCPI interface encounters a message terminator (LF)
the SCPI interface encounters a root specifier (:)
Active Header Path
In order to properly traverse the command tree, you must understand the concept of the active
header path. When the AC source is turned on (or under any of the other conditions listed above),
the active path is at the root. That means the SCPI interface is ready to accept any command at
the root level, such as OUTPut or STATe.
If you enter OUTPut, the active header path moves one colon to the right. The interface is now
ready to accept :STATe, :COUPling,:DFI, or :PROTection as the next header. You must include
the colon, because it is required between headers.
If you now enter :PROTection, the active path again moves one colon to the right. The interface is
now ready to accept either :CLEar or :DELay as the next header.
If you now enter :CLEar, you have reached the end of the command string. The active header
path remains at :CLEar. If you wished, you could have entered :CLEar;DELay 20 and it would be
accepted as a compound message consisting of:
1. OUTPut:PROTection:CLEAr and