Rockwell Automation 1785-Vx0B, D17856.5.9 PLC-5 VME VMEbus Programmable Controllers User Manual - Manual (Page 15)

Chapter 1
Overview
1-4
Use the PLC-5/VME processor in a 6U (full-height) VMEbus chassis. You
can use the PLC-5/VME processor by itself (i.e., with no other VME
modules), but typically the PLC-5/VME processor is used in conjunction
with other VMEbus computers (CPUs) and I/O modules. The examples
below illustrate possible configurations.
The PLC-5/VME processor is used in conjunction with a VMEbus CPU module. The
processor serves as a real-time I/O processor under the direction of the CPU. The
processor is a slave of the CPU, where, in addition to its normal ladder logic and I/O
processing in each scan loop, the processor responds to directions from the CPU and
passes data back to the CPU.
There is no fixed relationship between processor and CPU, so multiple CPUs can
communicate with one processor. Multiple CPUs run multiple tasks, all sending and
receiving data from the processor at the same time.
One CPU can control multiple PLC-5/VME processors. Each processor maps into the
VMEbus address space; so you map each processor to a different address space.
No CPU interacts with the processor. The processor interacts with I/O modules in one
or more remote I/O racks and has the capability, from its ladder program, of generating
VMEbus accesses. This means that the processor can access VMEbus I/O modules
as well.
System Description
19500
CPU
CPUs
DH+ link
PLC-5/VME
processor
PLC-5/VME processor
Remote I/O
or Extended-
Local I/O
19500
CPU
PLC-5/VME processor
PLC-5/VME processors