Rockwell Automation 1785-Vx0B, D17856.5.9 PLC-5 VME VMEbus Programmable Controllers User Manual - Manual (Page 17)

Chapter 1
Overview
1-6
The PLC-5/VME is fully compliant with the C.1 VMEbus specification.
The PLC-5/VME processor occupies two 6U VMEbus slots. It can reside
in any adjacent pair of slots, including slot 1, the system-controller slot.
The PLC-5/VME processor has a single VMEbus P1 connector, allowing it
to be used in VMEbus systems that have either the full J1 and J2
backplanes or only the J1 backplane.
The PLC-5/VME processor occupies 64 bytes in the VME A16 (or
“short”) address space, and you can configure an additional 64 Kbytes of
the A24 (or “standard”) address space.
The PLC-5/VME processor has 8 16-bit registers accessible in the VMEbus A16 address
space. A set of switches establishes the base address of these registers. These
registers can be used by a VMEbus CPU to establish certain programmable configuration
options of the processor, control and monitor certain low-level conditions, and send
commands to the processor.
The PLC-5/VME processor also has 64 KB of memory that can be enabled and mapped
in the VME A24 address space. This memory is a general-purpose memory that you can
use for any purpose (or not at all). If you enable it and tell the processor to do something
to a VME address that happens to fall into this 64KB memory, the processor can access it
without actually using VMEbus cycles. If you need some global VMEbus memory that
can be accessed by the processor and another CPU, there may be performance benefits
to using this 64KB of memory.
VMEbus Interface
Configuration/control/
status/message
registers in A16 space
Optional general-purpose
memory in A24 space
Processor
VMEbus