Quantum 890 USE 155 - Manual (Page 13)

Modbus to Ethernet Bridge
13
Figure 3 shows an example of message address mapping between a Modbus Master
and a Modbus Slave using two Bridges with an Ethernet link.
Figure 3 Mapping Modbus and IP Addresses
Modbus
Master
Modbus
Slave(s)
Ethernet
Bridge
A
B
Bridge
Modbus message to
Slave address 10
192.168.001.024
Bridge routes message to Slave
according to user–defined setup:
Message Slave Address (10)
or
Fixed Slave Address (1 ... 247)
Modbus – IP Address
Mapping Entry:
010 : 192.168.001.024
These are the events in the message routing:
H The Modbus Master sends its message containing address 10 decimal to
Bridge A.
H
You have set an entry in the mapping table in Bridge A. Your entry specifies that
messages with address 10 are to be mapped to IP address 192.168.001.024.
H Bridge B has that IP address and receives the message.
H Depending on the option you set in Bridge B, the message is routed either to
the Modbus Slave device at address 10 as specified in the message, or to a
fixed Slave address in the range 1 ... 247.