Schneider Electric 174 CEV - Manual (Page 45)

Configuring the Bridge
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3.9.2 Using Dynamic Routing
First setup the bridge for Host--based or Socket--based routing.
The bridge will now associate messages from the host’s IP address with the
Modbus Plus path you established, when you address those messages to the
Destination Index defined for the Host--based or Socket--based routing.
H Destination Index 0: Host--based routing After you setup the bridge for
Host--based routing from a TCP/IP host to a Modbus Plus path, any
messages from that host addressed to index 0 will be routed to that path.
The bridge maintains a cache of 10 associations between TCP/IP hosts and
Modbus Plus paths using Destination Index 0. Thus up to 10 hosts may set
associations and use them concurrently for transactions with Modbus Plus
nodes. If all 10 cache locations are in use and another host establishes an
association to index 0, the new association will overwrite the oldest one in
the cache.
This routing option allows the bridge to be configured for simple addressing
from TCP/IP nodes which do not support routing through gateways, such as
programming panels.
H Destination Index 254: Socket--based routing After you setup the bridge
for Socket--based routing from a TCP/IP host to a Modbus Plus path, any
messages from that host addressed to index 254 will be routed to that path.
The TCP/IP host can initiate messages to the Modbus Plus destination for
the duration of the host’s connection to the bridge. When the connection
terminates, the Modbus Plus path no longer exists for that TCP/IP host.
The bridge maintains up to 16 available socket connections, corresponding
to its eight Program and eight Data paths. For example, Modsoft panel
software uses both a Program and a Data path during its connection with the
bridge. The bridge will establish a socket for both paths during dynamic
routing, and will close the sockets when the connection is terminated.
This routing option allows the bridge to handle concurrent sessions from
multiple TCP/IP hosts using independent routing assignments. It provides a
means for your application to manage routing dynamically in addition to the
fixed routings you configure in the bridge’s TCP/IP to Modbus Plus mapping
table.