Keithley 6512, Instruction Manual, Page: 56 / 156

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3.1 Introduction
This section contains detailed information on programming
Model 6512 operating modes over the IEEE-488 bus. For ad-
ditional bus information, refer to the following sections of
the Appendix:
• IEEE-488 bus overview: Appendix A
• General bus commands: Appendix B
• Interface function codes: Appendix C
• Example computer programs: Appendix D
• Compatibility with Model 617 Electrometer: Appendix E
3.2 Device-dependent command
programming
IEEE-488 device-dependent commands are used with the
Model 6512 to control various operating modes such as func-
tion, range, trigger mode, and data format. Each command is
made up of a single ASCII letter followed by a number rep-
resenting an option of that command. For example, a com-
mand to control the measuring function (Volts, Ohms, Amps,
Coul) is programmed by sending an ASCII “F” followed by
a number representing the function option.
Multiple commands
A number of commands may be grouped together in one
string. A command string is usually terminated with an
ASCII “X” character, which tells the instrument to execute
the command string. Commands sent without the execute
character will not be executed at that time, but they will be
retained within an internal command buffer for execution at
the time the X character is received. If any errors occur, the
instrument will display appropriate front panel error messag-
es and generate an SRQ if programmed to do so.
Electrometer commands
Commands that directly affect the electrometer section (F, R,
C, Z, N, T, and A) will trigger a reading when the command
is executed. These bus commands affect the Model 6512
much like the front panel controls.
Order of command execution
Note that commands are not necessarily executed in the or-
der received; instead, they will be executed in the same order
as they appear in the status word:
Function (F); Range (R); Zero Check (C); Zero Correct (Z);
Suppress (N); Trigger (T); Reading Mode (B); Data Storage
(Q); SRQ Mode (M); EOI and Bus Hold-off (K); and Termi-
nator (Y).
Thus to force a particular command sequence, you would
follow each command with the execute character, as in the
example string, C1XZ1XC0X, which can be used to zero
correct the instrument.
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IEEE-488 Programming