Typical Command Sequences; Table F-3 Typical Bus Sequence; Table F-4 Typical Addressed Command Sequence - Keithley 6514 Instruction Manual

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. Table F-3 lists a typical bus sequence for sending the
addressed multiline commands. In this instance, the SDC command is being sent to the instru-
ment. 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 F-3
Typical bus sequence
Step Command
1 UNL
2 LAG*
3 SDC
4
*Assumes primary address = 14.
Table F-4 gives a typical common command sequence. In this instance, ATN is true while the
instrument is being addressed, but it is set high while sending the common command string.
Table F-4
Typical addressed command sequence
Step Command
1 UNL
2 LAG*
3 Data
4 Data
5 Data
6 Data
*Assumes primary address = 14.
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
IEEE-488 Bus Overview
Data bus
Hex Decimal
3F 63
2E 46
04 4
Data bus
Hex Decimal
3F 63
2E 46
2A 42
52 82
53 83
54 84
F-11