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M3i.48xx / M3i.48xx-exp Manual
Star-Hub introduction
Option Star-Hub (M3i and M4i only)
Option Star-Hub (M3i and M4i only)
Star-Hub introduction
The purpose of the Star-Hub is to extend the number of channels available for acquisition or generation by interconnecting multiple cards and
running them simultaneously.
The Star-Hub option allows to synchronize several cards of the same M3i/M4i series that are mounted within one host system (PC):
• For the M3i series there are the two different versions available: a small version with 4 connectors (option SH4) for synchronizing up to
four cards and a big version with 8 connectors (option SH8) for synchronizing up to eight cards.
• For the M4i series there are the two different mechanical versions available, with 8 connectors for synchronizing up to eight cards.
The Star-Hub allows synchronizing cards of the same family only. It is not possible to synchronize cards of
different families!
Both versions are implemented as a piggy -back module that is mounted to one of the cards. For details on how to install several cards in-
cluding the one carrying the Star-Hub module, please refer to the section on hardware installation.
Either which of the two available Star-Hub options is used, there will be no phase delay between the sampling clocks of the synchronized
cards and either no delay between the trigger events. The card holding the Star-Hub is automatically also the clock master. Any one of the
synchronized cards can be part of the trigger generation.
Star-Hub trigger engine
The trigger bus between an M3i/M4i card and the Star-Hub option consists of several lines. Some of them send the trigger information from
the card’s trigger engine to the Star-Hub and some receives the resulting trigger from the Star-Hub. All trigger events from the different cards
connected are combined with OR on the star-hub.
While the returned trigger is identical for all synchronized cards, the sent out trigger of every single card depends on their trigger settings.
Star-Hub clock engine
The card holding the Star-Hub is the clock master for the complete system. If
you need to feed in an external clock to a synchronized system the clock has
to be connected to the master card. Slave cards cannot generate a star-hub
system clock. As shown in the drawing on the right the clock master can use
either the programmable quartz 1 or the external clock input to be broadcast
to all other cards.
All cards including the clock master itself receive the distributed clock with
equal phase information. This makes sure that there is no phase delay be-
tween the cards.
Software Interface
The software interface is similar to the card software interface that is explained earlier in this manual. The same functions and some of the
registers are used with the Star-Hub. The Star-Hub is accessed using its own handle which has some extra commands for synchronization
setup. All card functions are programmed directly on card as before. There are only a few commands that need to be programmed directly
to the Star-Hub for synchronization.
The software interface as well as the hardware supports multiple Star-Hubs in one system. Each set of cards connected by a Star-Hub then
runs totally independent. It is also possible to mix cards that are connected with the Star-Hub with other cards that run independent in one
system.
Star-Hub Initialization
The interconnection between the Star-Hubs is probed at driver load time and does not need to be programmed separately. Instead the cards
can be accessed using a logical index. This card index is only based on the ordering of the cards in the system and is not influenced by the
current cabling. It is even possible to change the cable connections between two system starts without changing the logical card order that
is used for Star-Hub programming.
The Star-Hub initialization must be done AFTER initialization of all cards in the system. Otherwise the inter-
connection won’t be received properly.
