Studer D950 Operating Instructions Manual page 641

MADI Tasks
Fail Safe
Hot Plug-In
Date printed: 03.09.03
PE Tasks PE Tasks consist only of a DSP processing part. PE Tasks can run on both
PE and PEAES cards. The Card number of all PE Tasks is internally set to
zero (which has no effect). If there is no PE Card available, the PE Task
will be distributed to the next available PEAES Card.
MADI tasks can only run on MADI Cards. The Card number of the Task
must correspond to the Card number of the Card. Each MADI Task has a
unique Card number, which can be set with the Session Configuration
Tool if desired (otherwise, it starts with 00).
The Fail Safe principle allows automatic switchover of Tasks in case of a
Card failure. In other words, if a Card fails, another Card can take over
under the following conditions:
If a card hosting a task fails, the task will be redistributed applying the
rules above;
There must be a free Card in the system, conforming to the rules above.
Examples: The core houses 7 PEAES Cards. The currently loaded Session Config-
uration requires only 3 PEAES Tasks and 3 PE Tasks, leaving one PEAES
Card idle. We usually say there is one redundant card. There are 24
AES/EBU inputs and 24 AES/EBU Outputs configured.
Case 1: The sixth PEAES Card with a PE Task fails.
The seventh PEAES Card automatically takes over the full PE Task;
All DSP Channel functions are working.
⇒
All System functions restored!
Case 2: The second PEAES Card with the Card number 01 fails.
The seventh PEAES Card automatically takes over the full PEAES Task;
All DSP Channel functions are working;
The 8 AES/EBU Inputs and Outputs of the original card (connected to the
slot where Card 01 is) do not work.
⇒
System functions partially restored!
For case 2 above, several remedies can be taken:
If there is a spare AES/EBU Card on stock, the faulty PEAES Card can be
hot-unplugged and replaced by the new one, which can be hot-plugged. To
restore the original functionality after a card change, the new one must
have the correct Card number (01 according to the example above). The
spare card will take over the original PEAES Task, restoring the full sys-
tem functionality.
Simply plugging the AES/EBU cables into the right connectors corre-
sponding to the slot where the seventh card is will restore full system
functionality.
In all cases above, all the other Cards function properly, so that a Card
failure has only very limited consequences.
Another solution is to use the seventh card as a spare AES/EBU Card. In
this case, because the seventh card currently is in operation, the core must
be switched off before unplugging the seventh card. Now you can power
on the DSP rack again. The faulty PEAES Card can be unplugged and re-
placed by the seventh card. To restore the original functionality after a
card change, the new one must have the correct Card number (01 accord-
ing to the example above). The spare card will take over the original
PEAES Task, restoring the full system functionality.
SW V3.3
D950 Digital Mixing System
Troubleshooting/Maintenance 9-5