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22 | Ethernet / Serial Gateway - RS485-ETH-N
Figura 3.10: Client Mode Settings Screen
Server Mode Communication Example:
In this scenario, it is desired to take data from a device at address 192.168.1.101, that accepts MODBUS RTU query
from port no. 502, using a computer that is not connected to the network. MODBUS software in the computer
can create MODBUS ASCII queries. In this case, in oder to have a healthy data communication, the steps below
need to be followed:
1. MODBUS ASCII query created by the software in the computer is sent to RS485-ETH-N via serial port.
2. RS485-ETH-N receives MODBUS ASCII query from its Ethernet port and converts it to MODBUS TCP query.
3. RS485-ETH-N forwards the converted query to slave device via the Ethernet port and waits for the response
until timeout period expires (1 second is assumed to be enough for this scenario).
4. Slave device forwards the data that correspond to MODBUS TCP query and come from RS485-ETH-N to
RS485-ETH-N in the form of MODBUS TCP response from its Ethernet port. RS485-ETH-N receives the
MODBUS TCP response from the Ethernet port and converts it to MODBUS ASCII response.
5. RS485-ETH-N sends the converted MODBUS ASCII response to the computer via the serial port.
6. Software in the computer notifies the user by using MODBBUS ASCII response it receives from the network.
MODBUS ASCII
MODBUS ASCII
MODBUS TCP
MODBUS TCP
MODBUS TCP
MODBUS TCP
RS485-ETH-N
1 2 3
4 5 6
QUERY
RESPONSE
NETWORK
Figura 3.11: Client Mode Data Communication Scenario