Specifications

MBX Bridge Help

Cyberlogic Technologies Inc. - 20 -

The following configuration allows routing from Modbus Plus nodes to Modbus slave

nodes.

Source

Device Slave Path Filter

Destination

Device Network Type Routing Timeout

*.*.0.1-64.*

Modbus

MB4

5000

*.*.1.1-64.*

Modbus

MB4+64

5000

*.*.2.1-64.*

Modbus

MB4+128

5000

*.*.3.1-64.*

Modbus

MB4+192

5000

To see how this routing works, we will follow the case where the 984 controller at node

address 20 on the Modbus Plus network sends a message to the 984 controller at node

100 on the Modbus network.

1. The originating node sends a message with 5.1.1.36.0 routing. The first two routing

bytes (MB1, MB2) address the message to the MBX Bridge system’s PCI-85 at node

address 5, using slave path number 1.

2. The values of 1 and 36 in the third and fourth routing bytes (MB3, MB4) cause the

message to pass the Source Filter for the second routing record.

3. The Bridge routes the message to its destination. The routing record specifies that

the message is to be sent to Modbus MBX device 1. The Routing field calculates the

desired Modbus node address by adding 64 to the fourth byte in the Modbus Plus

routing address, resulting in an address of 100 for this message.

4. The message is delivered to its destination at Modbus node address 100. The

message is processed and the reply is sent back to the MBX Bridge, which passes it

over to the original Modbus Plus node at address 20.

Note

The expressions used in the Routing field for the four records allow messages to be

routed to all possible addresses on the Modbus network. Some Modbus Plus

applications will restrict the routing array bytes to values in the range 0-64. By

specifying 1, 2 or 3 as the third byte in the routing array, it is possible to stay within

this restriction and still obtain any destination Modbus address over the range of 0-256