Description:

The properties and advantages of multicomputing:

• Common K bus and common P bus in non-segmented module racks (central controllers) URL and URL.
• All CPUs work on one common I/O and communication bus, with automatic synchronization of the operating state transitions.
• A complex overall task can be split over up to 4 CPUs.
• Scalable performance increase is possible by simple slotting another CPU.
• Increase of system resources (memory, flags, counters, ...).
• Option of separating time-critical process part from non-time-critical process parts (e.g. rapid control of a fast closed-loop controller).
• Every I/O module is assigned to one specific CPU.
• Multicomputing is supported by S7-400 CPUs with the following order numbers:

Operation in the segmented module rack CR2

• The CPUs in the segmented module rack are each an independent subsystem and behave each like a separate processor, i.e. there is no multicomputing.
• The segmented module rack contains two separate P bus segments with 10 slots in Segment 1 and 8 slots in Segment 2.
• For each I/O bus segment one CPU is implemented, to which the I/O modules are assigned locally. The CPUs work independently of each other without synchronization of the operating state transitions.
• The common communication bus enables communication of subunits without additional hardware.
• Two separate controllers can thus be realized in one CR (space saving in the switchgear cabinet).
• Cost saved, because only one module rack and one power supply are required.

More information on this topics is available in

• Entry ID: 1117849 "SIMATIC S7-400 Programmable Controllers Hardware and Installation (installation manual)", section 2.3.
• Entry ID: 23904550 "SIMATIC Automation System S7-400 CPU Specifications", section 3.1.