Each ModbusTcpSlaveDevice you add under a ModbusTcpSlaveNetwork may have a Modbus address (1—247), although typically a Modbus TCP device uses only its unique IP address. When using the Modbus Tcp Slave Device Manager view to create new devices, the popup dialog allows you to enter this Modbus “Starting Address”, as shown in Figure 23.

Note this dialog allows you to add a sequentially-addressed range of multiple ModbusTcpSlaveDevices, by setting “Number to Add” more than 1, with the first device using the starting (Modbus) address. This technique may be useful in cases where you wish the station to appear as “multiple physical Modbus TCP devices” (each with a different set of proxy points)—however, note all devices are reached only through the station’s (same) host IP address.

More typically, you may wish to have the station appear simply as a single device, in which case you add only one ModbusTcpSlaveDevice. Note that you can specify many ranges of Modbus data items (coils, inputs, input registers, holding registers) in any or all ModbusTcpSlaveDevice components.

When you click OK in the dialog shown in Figure 23, the next New dialog provides a few “standard” new device properties to enter (such as Name and Enabled), and others common to all server Modbus devices (ModbusSlaveDevice, ModbusTcpSlaveDevice). For more details on these Modbus-related properties, see About Modbus server devices.