KEPCO TMA VXI-27 - Manual (Page 31)

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TMA VXI -27 101602
3.5.6 ADDRESSING MULTIPLE POWER SUPPLIES
Power supplies on the IEEE 1118 bus are selected by node address, also referred to as node
number or channel number. Refer to the applicable manuals for the power modules connected
to the IEEE 1118 bus to set each power module to a unique node number, from 1 to 31 (a max-
imum of 27 power modules may be connected to the bus).
The node number may follow any part of a SCPI command. Note that there must be no space
preceding the node number
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: 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).
3.5.7 UNDERSTANDING THE COMMAND STRUCTURE
Understanding the command structure requires an understanding of the subsystem command
tree illustrated in Figure 3-4. 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 TMA VXI-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