The following Ethernet communications interfaces are used in the various SIMATIC PCS 7 subsystems (ES, OS, AS etc.):

• Interfaces integrated onboard
• Simple network adapters
• Special communication modules, for example CP 1623 and CP 1628

These are defined when selecting the respective system components depending on the requirements. For further information, see Section "System connection of PCS 7 systems".

The communication stations can be integrated in the terminal bus and the plant bus using Industrial Ethernet Switches of the SCALANCE X product family. These switches offer scalable performance at an attractive price and support a wide variety of configuration options.

Configuration example for plant and terminal bus

Terminal bus

Client-server and server-server communication is carried out on a dedicated Ethernet LAN. The communication network identified as terminal bus can be implemented with standard SIMATIC NET components such as Industrial Ethernet switches, onboard interfaces, network adapters, communications processors (CP), cabling, etc.

A ring design avoids communication failures if e.g. the line is damaged or opened at a particular point. To further increase the availability, it is also possible to distribute the communication over two redundant rings. Each PCS 7 station is connected to one of two Industrial Ethernet ports on each of the two separate rings. The SIMATIC NET SOFTNET‑IE RNA communication software on the PCS 7 stations organizes communication processes based on the PRP. Non PRP-enabled devices that have only one Industrial Ethernet port, such as SICLOCK TC 400, can be integrated in the redundant terminal bus via SCALANCE X204RNA.

The Parallel Redundancy Protocol (PRP) according to IEC 62439-3 is based on double transmission of message frames over two separate networks (Ring 1, Ring 2). At the sender, the SOFTNET-IE RNA software or the SCALANCE X-200RNA network access point duplicates the message frame arriving from the sender and feeds one message frame to Ring 1 and the other to Ring 2. At the receiver, the software or the network access point forwards the first incoming message frame to the recipient. The second message frame from the second LAN is discarded. Transmission of the message frame is thus always ensured without delay if an error occurs.

Industrial Ethernet plant bus

The automation systems (AS) communicate with one another and with the engineering system and operator systems (servers/single stations) over the Industrial Ethernet plant bus. This can be configured in a similar way to the terminal bus, using SIMATIC NET standard components such as Industrial Ethernet switches, network adapters, communication modules (CP), cabling, etc. For small plants with up to eight standard automation systems per Operator System, single stations and servers can be efficiently operated on the plant bus using "Basic Communication Ethernet" (BCE) and a FastEthernet network adapter. The CP 1623/CP 1628 communication module is always required if more than eight automation systems or redundant automation systems are used.

As far as availability is concerned, ring topologies are always the first choice for the plant bus. With particularly high availability requirements, the plant bus can also be configured as a redundant double ring (two CPs per AS CPU and OS server). Double faults such as a switch failure on ring 1 with a simultaneous interruption in the bus cable on ring 2 can then be tolerated. The two rings in such a configuration are physically separated. The coupling partners are linked together logically when configuring with NetPro over a fault-tolerant S7 connection (4‑way redundancy). One switch each takes over the function of the redundancy manager for each ring. The current switches of the SCALANCE X‑500, X‑400, X‑300 and X‑200 product lines can act as redundancy manager in a ring.

Note:

Detailed information on Industrial Ethernet and on the network components can be found in Catalog IK PI, in the Industry Mall, or in Catalog CA 01 under "Industrial Communication".