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9 status subsystem, 10 system subsystem, 4 program message structure – KEPCO EL Series Electronic Load Operator Manual P/N 243-1295 Firmware Version 1.232 (Unit Rev 0 or 1) User Manual

Page 45: Figure 3-3. message structure, Status subsystem -11, System subsystem -11, Program message structure -11, Message structure -11

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SERIES EL 063010

3-11

3.10.3.9 STATUS SUBSYSTEM

This subsystem programs the Series EL status register. The electronic load has two groups of
status registers: Operation and Questionable. Each group consists of three registers: Condition,
Enable, and Event.

3.10.3.10 SYSTEM SUBSYSTEM

This subsystem controls various system functions.

3.10.4

PROGRAM MESSAGE STRUCTURE

SCPI program messages (commands from controller to load) consist of one or more message
units
ending in a message terminator. The message terminator is not part of the syntax; it is
defined by the way your programming language indicates the end of a line: “newline” must be
defined as CR (0D

H

) followed by LF (0A

H

). The message unit is a keyword consisting of a single

command or query word followed by a message terminator (e.g., CURR? or
INPut). The message unit may include a data parameter after the keyword sepa-
rated by a space; the parameter is usually numeric (e.g., CURR 5), but may also be a
string (e.g., OUTP ON). Figure 3-3 illustrates the message structure, showing how
message units are combined. The following subparagraphs explain each component of the
message structure.

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 3-3. MESSAGE STRUCTURE

CURR:RANG 1;:OUTP ON;:CURR?

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