Entry type: FAQ, Entry ID: 42650, Entry date: 04/21/2008
What is multicomputing mode and what are the differences to operating in the segmented subrack?
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:
|Module||Order number:||Order number: previous / discontinued|
|CPU 414-3 PN/DP||6ES7414-3EM05-0AB0|
|CPU 416-3 PN/DP||6ES7 416-3ER05-0AB0|
|CPU 416F-3 PN/DP||6ES7 416-3FR05-0AB0|
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.
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