Tektronix Keithley 2651A Reference Manual page 113

Section 2: General operation
SPE, SPD
Use the serial polling sequence to obtain the Model 2651A serial poll byte. The serial poll byte
contains important information about internal functions (see
the serial polling sequence is used by the controller to determine which of several instruments has
requested service with the SRQ line. The serial polling sequence may be performed at any time to
obtain the status byte from the Model 2651A.
Front-panel GPIB operation
This section describes aspects of the front panel that are part of GPIB operation, including messages,
status indicators, and the LOCAL key.
Error and status messages
The front-panel display may show error and status messages (see
messages (on page 2-71)). See
messages that are associated with IEEE-488 programming.
Communication status indicators
The remote (REM), talk (TALK), listen (LSTN), and service request (SRQ) indicators show the
communication bus status. Each of these indicators is described below.
Status indicator
REM
TALK
LSTN
SRQ
The SRQ applies to all available communication buses, however, actual service requests only apply
to GPIB, USB, and VXI-11 (see
information).
REM
This indicator is illuminated when the instrument is in the remote-control state. When the instrument is
in the remote-control state, all front-panel keys, except for the EXIT (LOCAL) key and OUTPUT
ON/OFF control, are locked out. When REM is off, the instrument is in the local-control state and
front-panel operation is restored.
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Model 2651A High Power System SourceMeter® Instrument Reference Manual
Error summary list
Applies to
GPIB, VXI-11, USB, RS-232
GPIB only
GPIB only
GPIB, VXI-11, USB
Status byte and service request (SRQ)
Status model (on page 15-1)). Generally,
Displayed error and status
(on page 8-3) for a list of status and error
(on page 15-15) for more
2651A-901-01 Rev. C October 2021