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EX2500A Trigger Mechanisms
77
VXI Legacy
The EX2500A is fully compatible with TTL and ECL trigger mechanisms which exists in VXI
chassis. The functionality of these trigger lines is not affected by the EX2500A and any instrument
synchronization currently established in a VXI chassis will remain when an EX2500A is used as a
slot 0 controller. In addition to supporting these VME backplane trigger, the EX2500A also
supports trigger via the LXI trigger bus as well as LXI LAN Events.
TTL/ECL Synchronization
Across Backplane
LXI Synchronization
Utilizing LXI Trigger Bus
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0
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VXI Mainframe
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34
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32
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LAN
POWER
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EX1016A
CH0 - CH15
CH16 - CH31
EX72SF
1588
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LAN
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1
2
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SW8
SW9
SW10
SW11
SW12
VTI
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A VXI Technology Business Unit
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LAN
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The last group of trigger sources/destinations reside in the LAN Event Trigger Controls section of
the
Trigger Configuration
page. LAN Events may only be sourced by the VXI Backplane’s TTL
Trigger lines (TTL0 – TTL7) or may be triggered via the web interface. The Destination Path is
defined in the
IVI LxiSync Interface Specification, section 5.2.2, Event Destination Path
. “The
default setting (empty string) is to send a multicast message to the default port. This is a comma
separated list of destinations. Each destination can be the keyword ‘all’ or an IP address or a
hostname. If an IP address or a hostame, then TCP is used instead of multicast. Each destination
can be followed by a “:” and a decimal port number. Each destination:port can be followed by and
optional “/” and an event id. Example: “all/DONE, 10.2.1.100:1234, dmm2.local/start” would
send a multicast event of DONE on the default port of 5044, a default LANx TCP event to host
10.2.1.100 port 1234, and a TCP event of “start” to host dmm2.local on the default port of 5044.
LAN Events are passed to other instruments through the eight LAN Event channels via Ethernet
packets (UPD/multicast or TCP messages) and are configured in a manner similar to the LXI
Trigger Bus. These events can occur in “past time” (not currently supported), “now”, or “future
time”. “Now” events have a IEEE 1588 time of “0”, indicating that the event will occur
immediately after it is received). Because they have a time of “0”, the event log will only identify
when this event was received. “Future time” events have an IEEE 1588 time that has not yet
occurred. Because these events occur in the future, they can be prepared for and provide a better
response time than either “past” or “now” events. For more information on LAN Events, please
see the LXI LAN Events in Section 5.
Although TTL trigger lines must be used as a direct LAN Event Trigger source, other sources may
still be used to indirectly trigger LAN Events. If, for example, the TTL0 trigger source is set to
LXI0 (and Invert is selected). If LAN0’s source is then set to TTL0, then LXI0 will trigger LAN0
indirectly via TTL0.
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