Siemens S5-135U/155U appendix Introduction, Coordinator

Multiprocessor Operation/Coordinators

6.1Introduction

The S5-135U/155U is a member of the SIMATIC S5 family of programmable (logic) controllers. The PLC can be used both in single and in multiprocessor operation with up to four CPUs.

Slots Occupied You can arbitrarily combine the CPUs in the central controller at the CPU slots.

CPU

CPU 948/CPU 928B/CPU 928

CPU 922

Slot Requirement

2slots 1 slot

In multiprocessor operation, each CPU processes its individual user program independently of the other CPUs.

The common S5 bus serves for data interchange with I/O modules, CPs, IPs and other CPUs. In multiprocessor operation, access of the CPUs to the S5 bus is controlled by a coordinator. The functioning of this module is described in Sections 6.5 and 6.6.

For an explanation of data interchange between CPUs in multiprocessor operation and the arrangement of your STEP 5 program, please consult the Programming Guide for your CPU.

Coordinator	A coordinator is required in multiprocessor operation. The following are
	available for the S5-135U/155U PLC:
	S 923A coordinator (COR A)
	and
	S 923C coordinator (COR C).
	The coordinator allocates to the CPUs the time divisions in which they can
	access the S5 bus (bus enable time), and contains the global memory for data
	interchange between the CPUs via communication flags. Additionally, the
	COR C contains another memory with four pages for the ªmultiprocessor
	communicationº function as well as a serial PG interface with PG
	multiplexer function (PG MUX).

6-2	System Manual
	C79000-G8576-C199-06