Bus coupler

This catalog is out of date, see note on page 2

Description

Fig. 4/18 Bus coupler (BK-FF), subrack configuration

Application

Bus couplers are used for data transfer between participants on independent remote buses (BK-FF). They enable decoupling of the data transfer on the buses as well as distances between two participants up to 3 x 4 km.

The bus line can be single or redundant. Bus couplers can also be used in parallel to increase the transmission performance. A maximum of two bus couplers may be connected in series be- tween two participants which exchange information.

Parallel bus couplers

If the coupling capacity of a bus coupler is not sufficient, the transmission performance can be increased by approx. 100% by using a second bus coupler. This parallel connection of bus couplers leads to limitations in performance if one of them fails (this is not a redundant connection).

Redundant bus couplers

If the coupling capacity of a bus coupler is sufficient, a redun- dant system can be produced using a second bus coupler. In this case, the second bus coupler automatically takes over the coupling function if the first bus coupler fails.

Design

The bus coupler consists of

-- 2 interface modules for bus coupler (N-BK), -- power supply module and

-- 2 or 4 bus converters UI for remote bus coupling (BK-FF) depending on whether the remote buses are of single or redundant design.

All these modules are fitted in a double-height subrack. This is completely wired and equipped with all necessary plugs and guide rails.

Mode of operation

A bus coupler acts like any other participant on the bus. It has an address on every bus. A participant on bus 1 sends a mes- sage to a participant on bus 2 by first addressing the bus cou- pler. This stores the message briefly independent of the current message transfer on bus 2 and acknowledges receipt to the transmitting participant.

The bus coupler transmits the message on bus 2 if it becomes the master on this bus. The participant to which the message is addressed accepts the message and acknowledges receipt to the bus coupler.

Redundant remote bus 1

e. g.	e. g.
Bus address 1	Bus address 1
Participant address 5	Participant address 6
e. g.	e. g.
Bus address 1	Bus address 2
Participant address 5	Participant address 12

Redundant remote bus 2

BK Bus coupler

UI Bus converter

Fig. 4/19 Parallel bus couplers, e. g. between redundant remote buses

Siemens PLT 130 . 1994

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