Typical Command Sequences - Keithley 2750 User Manual

G-12 IEEE-488 Bus Overview

Typical command sequences

For the various multiline commands, a specific bus sequence must take place to properly
send the command. In particular, the correct listen address must be sent to the instrument
before it will respond to addressed commands.
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 G-3
Typical addressed command sequence
*Assumes primary address = 16.
Table G-4
the instrument is being addressed, but it is set high while sending the common command
string.
Table G-4
Typical addressed command sequence
*Assumes primary address = 16.
Step Command
1 UNL
2 LAG*
3 SDC
4
gives a typical common command sequence. In this instance, ATN is true while
Step Command
1 UNL
2 LAG*
3 Data
4 Data
5 Data
6 Data
Model 2750 Multimeter/Switch System User's Manual
Table G-3
ATN state ASCII
Set low ?
Stays low '
Stays low EOT
Returns high
ATN state ASCII
Set low ?
Stays low '
Set high *
Stays high R
Stays high S
Stays high T
lists a typical bus sequence for
Data bus
Hex Decimal
3F 63
36 54
04 4
Data bus
Hex Decimal
3F 63
36 54
2A 42
52 82
53 83
54 84