Quantum 890 USE 155 - Manual (Page 10)

Modbus to Ethernet Bridge
10
1.1
Introducing the Modbus to Ethernet Bridge
1.1.1 Bridge Applications
The Modicon Modbus to Ethernet Bridge provides a means for transacting messages
between Ethernet TCP/IP devices and Modbus serial devices. It supports up to eight
concurrent transactions between Modbus Master and Slave devices, handling the
conversion of TCP/IP and Modbus RTU/ASCII protocols transparently to the user
application.
Ethernet nodes using TCP/IP can function as Modbus Masters, originating messages
to the Bridge for delivery to Modbus Slave devices connected to the Bridge’s Modbus
port. The Bridge forwards the messages to the Slave devices using Modbus RTU or
ASCII protocol and returns their responses to the Master.
Figure 1 shows a typical application in which a Bridge connects two Modbus Masters
on Ethernet to several Modbus Slave serial devices.
Figure 1 Bridging Between Ethernet and Modbus
Ethernet
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Modbus
Bridge
The bridge also allows multiple Modbus networks to be linked together across an
Ethernet connection. Multiple Bridges can furnish an Ethernet link between widely
separated Modbus networks. This extends the message path beyond the cable
lengths allowed for serial connections, and allows a Master on any Modbus network to
access Slave devices on another network.