KEPCO MST 488 Programmer - Manual (Page 37)

MST488-27 013004
3-11
e.g.,
meas2:volt?
or
meas:volt2?
both measure output voltage of the power supply at node
number 2.
e.g.,
func3:mode volt
or
func:mode3 volt
both set the power supply at node number 3 to
commanded voltage mode.
e.g.,
stat1:ques?
or
stat:ques1?
or
stat:ques:cond1?
all read Questionable Register
status of the power supply at node number 1.
Upon power turn-on, commands sent without a node (channel) number will go to the default
node address (1) until another node number is specified. Once another node number is speci-
fied, the new number becomes the default until another is specified.
NOTE: An alternate means of selecting the node, is to use IEEE 488 secondary addressing,
where the secondary address is the power supply node address (refer to PAR. 2.2.2 to
enable this feature).
The node selected can also be changed using the INSTrument:SELect <N> command.
This allows subsequent commands to operate on the specified node (e.g. INST:SEL 10
causes node 10 to be selected).
3.4.6 UNDERSTANDING THE COMMAND STRUCTURE
Understanding the command structure requires an understanding of the subsystem command
tree illustrated in Figure 3-2. The “root” is located at the top left corner of the diagram. The
parser goes to the root if:
• a message terminator is recognized by the parser
• a root specifier is recognized by the parser
Optional keywords are enclosed in brackets [ ] for identification; optional keywords can be omit-
ted and the power supply will respond as if they were included in the message. The root level
keyword [SOURce] is an optional keyword. Starting at the root, there are various branches or
paths corresponding to the subsystems. The root keywords for the MST 488-27 controller are
:INITiate, :MEASure, :OUTPut, [:SOURce], :STATus, and :SYSTem. Because the [SOURce]
keyword is optional, the parser moves the path to the next level, so that VOLTage, CURRent,
and FUNCtion commands are at the root level.
Each time the parser encounters a keyword separator, the parser moves to the next indented
level of the tree diagram. As an example, the STATus branch is a root level branch that has
three sub-branches: OPERation, PRESet, and QUEStionable. The following illustrates how
SCPI code is interpreted by the parser:
STAT:PRES<NL>
The parser returns to the root due to the message terminator.
STAT:OPER?;PRES<NL>
The parser moves one level in from STAT. The next command is expected at the level defined
by the colon in front of OPER?. Thus you can combine the following message units
STAT:OPER? and STAT:PRES;
STAT:OPER:COND?;ENAB 16<NL>
After the OPER:COND? message unit, the parser moves in one level from OPER, allowing the
abbreviated notation for STAT:OPER:ENAB.