Operation
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6.5.
MODBUS TCP MASTER
When the ControlNet Router has the Ethernet Mode set to Modbus TCP Master, then the
ControlNet data can be mapped to and from configurable internal Modbus Registers using
the Internal Map.
The internal Modbus Registers are then asynchronously exchanged with up to 20 Modbus
devices as configured in the Modbus Auxiliary Map. In this mapping the user can exchange
(read or write) data between the internal Modbus Registers and a remote Modbus device.
In the example below the ControlNet Router with the Ethernet Mode set to Modbus TCP
Master will read multiple Modbus Holding Registers from a Modbus Slave device and then
map the received data to a ControlNet Input assembly where the module ControlNet Mode
is set to Target.
Figure 6.13
–
Modbus Master to ControlNet operation
For this example the user will configure the Modbus Auxiliary Map to read data from a
Modbus Slave device. The ControlNet Router will request data from Modbus Holding Register
4000 (from the external Modbus Slave) and write it to the module’s internal Modb
us Holding
Register 3000.