Universal Multiline Commands - Keithley 2182 User Manual

F-8 IEEE-488 Bus Overview
Figure F-3
ATN (Attention) — The controller sends ATN while transmitting addresses or multiline
Command
commands.
codes
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 commands 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
their 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.