Each ModbusSlaveDevice you add under a ModbusSlaveNetwork requires a Modbus address (1—247) unique from any other physical device on that network. When using the Modbus Slave Device Manager view to create new devices, the popup dialog allows you to enter this “Starting Address”, as shown in Figure 20.

Note this dialog allows you to add a sequentially-addressed range of multiple ModbusSlaveDevices, 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 devices” (each with a different set of proxy points).

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

When you click OK in the dialog shown in Figure 20, 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 client devices.