Appendix E
Modifying and Installing I/O Expansion Boards
E-2
©
National Instruments Corporation
Length of VXIpc-850 Plug-In Boards
The VXIpc-850 will accommodate PCI or ISA I/O boards that are up to
4.2 in. high and up to 13.415 in. long when DRAM SIMMs 0.85 in. or
shorter are used on the processor board (National Instruments provides
0.85 in. SIMMs). Due to slight variances in I/O board geometries,
however, take care in every application to identify possible contact with
the SIMMs. The maximum recommended board length is 7.72 in. if you
are using SIMMs taller than 0.85 in. If you want to install a longer board
with taller system DRAM SIMMs, you must consider the strong
possibility of contact with the SIMMs.
Because DRAM SIMMs taller than 0.85 in. are more likely to interfere
with ISA cards than PCI cards, the two are discussed separately in the
following sections.
Length of PCI Plug-In Boards
The VXIpc-850 accommodates any standard 32-bit, 5 V PCI I/O board.
The maximum standard dimensions of a PCI I/O board are 12.283 in. by
4.2 in. PCI cards are installed in the VXIpc-850 such that the board
components face the processor card, which contains the processor and
system RAM. Exceptionally tall PCI components (higher than 0.52 in.)
on a plug-in board may physically contact the DRAM SIMMs installed
on the CPU card, as shown in Figure E-2.
Figure E-2.
Component Height Restrictions for PCI Plug-In Boards
Used with the VXIpc-850
Because larger DRAM sizes may employ taller SIMMs, you must be
careful that the component height of the PCI board does not interfere
with the SIMMs in such a way that electrical shorts occur or that the PCI
board is stressed enough to compromise its physical or electrical
integrity.
PCI Card
Riser Card
Heat Sink
Front Panel
Possible Support
Bracket Positions
.85 in. High
SIMMs
VXI Connector
.62 in. max to Heat Sink
.52 in. max to SIMMs
