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F-8
ATN (Attention) — The controller sends ATN while transmitting addresses or multiline
commands.
SRQ (Service Request) — SRQ is asserted by a device when it requires service from a
controller.
Universal multiline commands
Universal commands are those multiline commands that require no addressing. All
devices equipped to implement such commands will do so simultaneously when the com-
mands are transmitted. As with all multiline commands, these commands are transmitted
with ATN true.
LLO (Local Lockout) — LLO is sent to the instrument to lock out the LOCAL key and all
front panel controls.
DCL (Device Clear) — DCL is used to return instruments to some default state.
Instruments usually return to their power-up conditions.
SPE (Serial Poll Enable) — SPE is the first step in the serial polling sequence which is
used to determine which device has requested service.
SPD (Serial Poll Disable) — SPD is used by the controller to remove all devices on the
bus from the serial poll mode and is generally the last command in the serial polling
sequence.
Addressed multiline commands
Addressed commands are multiline commands that must be preceded by the device listen
address before that instrument will respond to the command in question. Note that only the
addressed device will respond to these commands. Both the commands and the address
preceding it are sent with ATN true.
SDC (Selective Device Clear) — The SDC command performs essentially the same
function as the DCL command except that only the addressed device responds. Generally,
instruments return to their power-up default conditions when responding to the SDC
command.
GTL (Go To Local) — The GTL command is used to remove instruments from the
remote mode. With some instruments, GTL also unlocks front panel controls if they were
previously locked out with the LLO command.
GET (Group Execute Trigger) — The GET command is used to trigger devices to per-
form a specific action that depends on device configuration (for example, take a reading).
Although GET is an addressed command, many devices respond to GET without
addressing.
Model 2790 SourceMeter
®
Switch System Reference Manual
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