B&B Electronics Vlinx MESR9xx - Manual (Page 33)

4. Properties Vlinx MESR9xx Modbus Gateway
Page 29 Manual Documentation Number MESR9xx-4508m
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• For a Class D network (IP addresses 224.0.0.0 through 239.255.255.255) and
Class E Networks (IP addresses 240.0.0.0 through 255.255.255.255) the subnet
mask is ignored.
• MESR9xxModbus Gateways come from the factory with a default subnet mask
value of: 255.255.255.0
TCP (Transmission Control Protocol)
TCP (Transmission Control Protocol) provides reliable connection-oriented network
communication with error checking. In TCP mode the Modbus gateway can be
configured as a client or a server.
When the Modbus gateway is configured as a TCP client it initiates connections with a
server on the network. You must set up the IP address and port number of the server that
you want the client (Modbus gateway) to communicate with. You also select whether the
Modbus gateway is to connect at power up or only when it receives data from the device
connected to its serial port.
When the Modbus gateway is configured as a TCP server it waits for connections to be
initiated by another network device. You must set up the TCP port number that it will
listen to for connections and set the maximum (up to eight) number of simultaneous
connections it will accept. You can filter the connections it will accept based on specific
IP addresses or ranges of IP addresses that you specify.