4-16
BIT 4886 051010
NOTE: An alternative to using the message structure for multiple messages defined in the fol-
lowing paragraphs is to send each command as a separate line. In this case each com-
mand must use the full syntax shown in Appendix B.
FIGURE 4-6. MESSAGE STRUCTURE
4.6.4.1
KEYWORD
Keywords are instructions recognized by a decoder within the Interface Card, referred to as a
“parser.” Each keyword describes a command function; all keywords used by the Interface Card
are listed in Figure 4-5.
Each keyword has a long form and a short form. For the long form the word is spelled out com-
pletely (e.g. STATUS, OUTPUT, VOLTAGE, and TRIGGER are long form keywords). For the
short form only the first three or four letters of the long form are used (e.g., STAT, VOLT, OUTP,
and TRIG).
To identify the short form and long form in this manual, keywords are written in upper case let-
ters to represent the short form, followed by lower case letters indicating the long form (e.g.,
IMMediate, EVENt, and OUTPut). The parser, however, is not sensitive to case (e.g., outp,
OutP, OUTPUt, ouTPut, or OUTp are all valid).
You must use the rules above when using keywords. Using an arbitrary short form such as
ENABL for ENAB (ENABLE) or IMME for IMM (IMMEDIATE) will result in an error. Regardless
of which form chosen, you must include all the letters required by that form.
4.6.4.2
KEYWORD SEPARATOR
If a command has two or more keywords, adjacent keywords must be separated by a colon (:)
which acts as the keyword separator (e.g.,
CURR:LEV:TRIG
). The colon can also act as a root
specifier (paragraph 4.6.4.7).
:CURR:LEV 3.5;:OUTP ON;:CURR?<NL>
MESSAGE TERMINATOR
KEYWORD
QUERY INDICATOR
ROOT SPECIFIER
MESSAGE UNIT SEPARATOR
DATA
KEYWORD
KEYWORD
KEYWORD SEPARATOR
KEYWORD
MESSAGE UNIT SEPARATOR
DATA
MESSAGE UNIT
DATA SEPARATOR
DATA SEPARATOR
ROOT SPECIFIER
INITIAL ROOT
SPECIFIER IS
OPTIONAL
