Section 3: Functions and features
Model 2461 Interactive SourceMeter® Instrument Reference Manual
3-100
2461-901-01 A/November 2015
Command interface triggering does not generate action overruns. The triggers are processed in the
order that they are received in the Model 2461 command queue. The Model 2461 only processes
incoming commands when no commands are running. Unprocessed input triggers can cause an
overflow in the command queue. It is important to make sure a script processes triggers while it is
running.
If you are using a test script using TSP, the command queue can fill up with trigger entries if over 50
*TRG
messages are received while a test script is running, even if the script is processing triggers.
You can avoid this by using the
(on page 8-97) attribute, and by using
trigger.wait()
calls that remove the
*TRG
messages from the command queue. If the command
queue fills with too many trigger entries, messages such as
abort
are not processed.
Triggering using hardware lines
You can use the digital I/O lines and TSP-Link
®
synchronization lines to synchronize the operations of
the Model 2461 with those of external instruments. You can use these lines to synchronize the Model
2461 with other TSP-enabled instruments, including other Model 2461 instruments. You must use the
digital I/O lines to synchronize the Model 2461 with other Keithley products or other non-Keithley
products.
The lines are configured and controlled similarly. See
Connecting the Model 2461 to a Trigger Link system
(on page 3-93)
for more information about connections and configuration and control of the lines.
LAN triggering overview
You can send and receive triggers over the LAN interface. The Model 2461 supports LAN extensions
for instrumentation (LXI). It has eight LAN triggers that generate and respond to LXI trigger packets.
Understanding hardware value and pseudo line state
LAN triggering and hardware synchronization are similar, except that LAN triggering uses LXI trigger
packets instead of hardware signals. A bit in the LXI trigger packet called the hardware value
simulates the state of a hardware trigger line. The Model 2461 stores the hardware value as the
pseudo-line state. Only the state of the last LXI trigger packet that was sent or received is stored.
The stateless event flag is a bit in the LXI trigger packet that indicates if the hardware value should be
ignored. If it is set, the Model 2461 ignores the hardware value of the packet and generates a trigger
event. The Model 2461 always sets the stateless flag for outgoing LXI trigger packets. If the stateless
event flag is not set, the hardware value indicates the state of the signal.
The instrument interprets changes in the hardware value of consecutive LXI trigger packets as edge
transitions. Edge transitions generate trigger events. If the hardware value does not change between
successive LXI trigger packets, the Model 2461 assumes an edge transition was missed and
generates a trigger event. The following table shows edge detection in LAN triggering.