Installation guide

Introducing the Modbus Plus Network
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1.5.7 BM85 Bridge Multiplexer
The BM85 Bridge Multiplexer provides connection to Modbus Plus for
up to four kinds of serial devices. Four BM85 models are available.
Two of these connect Modbus devices, or networks of Modbus devices, to
the Modbus Plus network. Each of the Modbus ports can be separately
configured to support a Modbus master device, slave device, or network
of slave devices. Port parameters are also separately configurable.
Two other BM85 models are available for user-defined RS232 or RS485
serial devices. They include a library of C language functions for
creating a user application program.
Bridge Multiplexers are available for single-cable and dual-cable
network layouts. Contact your Modicon distributor for information
about models and part numbers.
1.5.8 BP85 Bridge Plus
The BP85 Bridge Plus allows you to connect two Modbus Plus
networks. The routing information in each message allows a node on
one network to communicate through the Bridge Plus to a destination
node on another network. Up to four bridges can be present in the
message path between the source and destination nodes. You can
therefore join up to five Modbus Plus networks along a linear path,
with any node being able to communicate with any other node.
Bridge Plus devices are not applicable to Modbus Plus DIO networks
because those networks transfer data messages as part of the token
pass. Tokens are not passed through the Bridge Plus.
Note that the Bridge Plus may still be placed on a DIO network to
allow non-DIO messages to be passed to another network. For
example, statistical reporting can be handled between a controller on
the DIO link and a network adapter in a host processor on another
network.
The Bridge Plus contains two ports, for connection to its two networks.
It functions as an addressable node on each of the two networks it
joins. It contains two sets of address switches, for setting its node
address on each network. The two addresses can be set to the same
value, or to different values, as they are independent of each other.
Bridge Plus models are available for single-cable and dual-cable
network layouts. Contact your Modicon distributor for information
about models and part numbers.