User Manual Host Adapter SIMATIC TIWAY 1

CONFIGURING THE HOST COMPUTER PORT

UNILINK HOST

ADAPTER 3–6

USER MANUAL

3.2.3 Multidrop

Host Inter

face Cir

cuit

You can multidrop up to 32 adapters using modems in a multipoint circuit as

shown

in Figure 3–6. This allows the

host computer to control multiple TIW

Y I

networks; however, each adapter must use the BDLC protocol. Each adapter

must be assigned a unique address with dipswitches. The BDLC protocol uses

the addresses to route messages to the correct network. A multipoint circuit

represents the network layer of the Open Systems Interconnection model

described further in Reference 4 in the Preface and in the TIWAY I Systems

Manual

(PPX:TIW

AY–8101).

Host

Computer

Modem Modem

Modem

UNILINK

Host Adapter

UNILINK

Host Adapter

UNILINK

Host Adapter

TIWAY1

Network #1

TIWAY1

Network #2

TIWAY1

Network #3

4-wire leased line

or equivalent wire

Figure 3–6 Multidrop Host Interface Circuit

NOTE

You should select half-duplex operation for the

modems

when you

multidrop to prevent the network

modems from simultaneously raising the carrier.