Lan Triggering Overview - Keithley 2651A Reference Manual

Section 3: Functions and features
Assigning input trigger events
Each event blender has four stimulus inputs. A different trigger event ID can be assigned to each
stimulus input. The programming example below illustrates how to assign the source complete event
ID of SMU A and the trigger event ID of digital I/O line 1 to stimulus inputs 1 and 2 of event blender 1:
trigger.blender[1].stimulus[1] = smua.trigger.SOURCE_COMPLETE_EVENT_ID
trigger.blender[1].stimulus[2] = digio.trigger[1].EVENT_ID
Action overruns
Action overruns are generated by event blenders depending on the mode, as shown in the following
table.
Action overruns
Mode
And
Or

LAN triggering overview

Triggers can be sent and received over the LAN interface. The Model 2651A supports LAN
extensions for Instrumentation (LXI) and has eight LAN triggers that generate and respond to LXI
trigger packets.
Understanding hardware value and pseudo line state
LAN triggering is very similar to hardware synchronization except LXI trigger packets are used instead
of hardware signals. The hardware value is a bit in the LXI trigger packet that simulates the state of a
hardware trigger line. The Model 2651A stores the hardware value of the last LXI trigger packet sent
or received as the pseudo line state.
The stateless event flag is a bit in the LXI trigger packet that indicates if the hardware value should
be ignored. If set, the Model 2651A ignores the hardware value of the packet and generates a trigger
event. The Model 2651A always sets the stateless flag for outgoing LXI trigger packets. If the
stateless event flag is not set, then the hardware value indicates the state of the signal. Changes in
the hardware value of consecutive LXI trigger packets are interpreted as edge transitions. Edge
transitions generate trigger events. If the hardware value does not change between successive LXI
trigger packets, the Model 2651A assumes an edge transition was missed and generates a trigger
event. The following table illustrates edge detection in LAN triggering.
Instruments that are compliant to LXI versions prior to 1.2 always process the hardware value.
Instruments compliant to LXI version 1.2 and later are required to ignore the hardware value when the
stateless event flag is set.
3-50
Model 2651A High Power System SourceMeter® Instrument Reference Manual
Action overrun
Generates an overrun when a second event on
any of its inputs is detected before generating
an output event.
Generates an overrun when two events are
detected simultaneously.
NOTE
2651A-901-01 Rev. A / March 2011