Chapter 6 - 16-Bit Ethernet Installation (XVME-956/411)
Function
Default
Jumper
Position
TERMINATION
DISABLED
W1
DOWN
BUS SIZE
AUTO
W2
LEFT
6.2.1 J u m p e r Settings
Table 6-1. Default Jumper Configuration
Termination
The 10Base2 input (BNC) can be terminated on the XVME-956/411 card. This eliminates the need for
the TEE fitting + BNC terminator at the end of the line, and is very convenient for simple two or three
node nets. T h e on-card termination should not be used if the Ethernet cabling is subject to frequent
change, as it is easy to forget that a card is terminated internally. The internal termination is enabled
by setting the shorting jumper on jumper block W1 in the UP position. Setting the jumper to the
DOWN position disables the internal termination.
Bus Size Selection
The XVME-956/411 can work with 8 and 16 bit CPUs. Bus size is normally selected automatically by
sensing the voltage on the PC/104 bus J2 connector pin 34. This is a 5V line on the AT part of the bus
connector. I f 5V is sensed on this line, an AT type CPU is assumed, and 16 bit bus transfers are used.
If the shorting jumper on jumper block W2 is placed in the left hand position, automatic bus sizing is
enabled. I f the shorting jumper is placed in the right hand position, the XVME-956/411 is forced into
the 8 bit mode.
6-2
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