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Common commands
Common commands are commands that are common to all devices on the bus. These com-
mands are designated and defined by the IEEE-488.2 standard.
Generally, these commands are sent as one or more ASCII characters that tell the device to
perform a common operation, such as reset. The IEEE-488 bus treats these commands as data
in that ATN is false when the commands are transmitted.
SCPI commands
SCPI commands are commands that are particular to each device on the bus. These com-
mands are designated by the instrument manufacturer, and are based on the instrument model
defined by the Standard Commands for Programmable Instruments (SCPI) Consortium’s SCPI
standard.
Generally, these commands are sent as one or more ASCII characters that tell the device to
perform a particular operation, such as setting a range or closing a relay. The IEEE-488 bus
treats these commands as data in that ATN is false when the commands are transmitted.
Command codes
Command codes for the various commands that use the data lines are summarized in Figure
E-3. Hexadecimal and the decimal values for the various commands are listed in Table E-2.
Table E-2
Hexadecimal and decimal command codes
Command Hex value Decimal value
GTL
SDC
GET
LLO
DCL
SPE
SPD
LAG
TAG
SCG
UNL
UNT 01
04
08
11
14
18
19
20-3F
40-5F
60-7F
3F
5F 1
4
8
17
20
24
25
32-63
64-95
96-127
63
95
IEEE-488 Bus Overview E-11