Specifications

EPC-5A Hardware & Software Reference Manual
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Installing the VMEbus Backplane Jumpers
The VMEbus specification provides four bus grant signals (BG0 - BG3) and one
interrupt acknowledge signal (
IACK) via daisy-chain lines. Per the VMEbus
specifications, all boards (that plug into the backplane) are required to correctly
handle these signals. All slots that do not have a board plugged into the backplane
(i.e. empty slots and slots occupied by EXMs or mass storage modules), need to be
jumpered to allow the signals to pass through to other boards in the system.
xxxOUT
xxxIN
xxxOUT
xxxIN
xxxOUT
xxxIN
VMEbus Slots
xxxIN
xxxOUT
Figure 2-2. Daisy-Chain Signal Concept.
The Slot-1 controller board initiates each daisy-chain signal. Each VMEbus slot to
the right of the Slot-1 controller must pass through each of the daisy-chain signals.
For each VMEbus slot,
xxxIn pin must be connected to its corresponding xxxOut
pin (e.g. BG0In to BG0Out, BG1In to BG1Out,...,IackIn to IackOut)
either through the board in that slot or by jumpers. Some boards correctly pass all of
these signals, some boards handle some of these signals and not others, and some
boards (typically “dumb” slave boards) may not handle any of these signals. Check
the manual for each board to be installed to determine if these signals are passed
through correctly. If they are not, or if the VMEbus slot is empty, all (or some) of
these signals must be jumpered. See the following figures for examples.