VME EXPANSION MODULE
~
This
chapter
describes
the
VME Expansion
Module
and
its VME
board
add-on
options.
The VME Expansion
Module
is
an
expansion
module
containing four single
wide
VME
board
slots. These
modules
and
their backplanes are connected to
the
bottom
of
the
CPU
Module
or
the
bottom
of the last
expansion
module.
The
VME
terminator
is
built
into
the
Base.
Additions
to a single
module
enclosure
can
be
done
by
latching
additional
VME Expansion
Modules
under
the
existing module.
VME Backplane
A
backplane
is
mounted
in
every
VME Expansion Module. There
are
two
types of backplanes,
one
for
the
CPU
Module
and
another
one for
the
VME
Expansion Module.
The
CPU
Module
backplane
has
receptacle connectors
at
the
bottom
of the
module
but
no
connectors
at
the
top
for interconnection. The
backplanes
have
a direct connection to the
power
supply
through
a
press
fit
96-pin connector identical to
the
connector
used
for VME
bus
Pl.
Connections
Board connections to the
backplane
are
made
via
standard
96-pin
DIN
connectors. Internal connections
are
allowed
to
the
A
and
C
rows
of VME
bus
J2
by
having
long
pins
on
the
J2
connector.
External connections consist of
pairs
of 4-row 140-pin
Eurocard
connectors.
Pin
connectors are
at
the
top
of
every
VME Expansion
Module
backplane
and
receptacle connectors are
on
the
bottom
of
every
VME Expansion
Module
backplane. These connectors
provide
the
total signal interconnection
between
the
VME Expansion
Modules
and
also
the
interconnection to
the
terminator
in
the
base.
The
A
row
of
pins
in
both
140
pin
connectors are
dedicated
to
the
interconnection of signal
ground
between
modules. These
70
pins
behave
as a
ground
plane. They
do
not
behave
as
separate
contacts
in
parallel
due
to
their
physical topology. Therefore,
the
impedance
of this
ground
plane
interconnect
is
much
lower
than
the
impedance
of a single A
row
contact
divided
by
140.
This is necessary to allow
the
ground
referenced VME
bus
to work.
S900RF/D4
3-1
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
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