Keithley 486 Instruction Manual page 228

APPENLNXE
IEEE-488 Bus Overview
Table E-2. Hexadecimal and Decimal
Command Codes
:ommmd
GTL
SIX
GET
LLO
DCL
SPE
SI'D
E
SGG
Hex Value
01
04
08
11
14
18
19
ZO-3F
40-5F
64vF
3F
5F
I
Decimal Value
1
4
8
17
20
24
25
32-63
64-95
96-127
63
95
In particular, the correct listen address must be sent to the
instrument before it will respond to addressed corn-
mands. Table E-3 lists a typical bus sequence for sending
the addressed multiline commands. In this instance, the
SDC command is being sent to the instrument. UNL is
generally sent as part of the sequence to ensure that no
other active listeners are present. Note that ATN is true
for both the listen command and the SDC command byte
itself.
Table E-4 gives a typical device-dependent command se-
quence. In this instance, ATN is true while the instru-
ment is being addressed, but it is set high while sending
the device-dependent command string.
IEEE Command Groups
Typical Command Sequences
For the various multiline co nummls, a specific bus se-
quence must take place to properly send the command.
Command groups supported by the Model 486/487 are
listed in Table E-5. Device-dependent commands are not
included in this list.
Table E-3. Typical Addressed Command Sequence
I I I I
Step Command ATNState ASCII
I I I
R-EzEi
*Assumes primary address = 22
Table E-4. Typical Device-dependent Command Sequence
Step
Command
ATNState
I I I I I
63 54
L
82
48
88
E-7