Abstract: Modbus Remote Monitoring and Control usually uses RS-485 and RS-232 transport for collecting data from Modbus slaves using established protocols. Of the two, Modbus RS-485 is more common due to its support for multi-drop communication. In this research the user defined function is analyzed, which can efficiently configure the serial parameters like buadrate, parity and slave address, of the any Modbus slave connected to modbus master in multi-drop network. With this function data switching work can be done in more flexible ways with configurable serial parameters. For better commercial usage of the modbus, the master should efficiently communicate and configure the any modbus slave attached to the multi-drop network. This user defined function is more fast and economical way to configure serial parameters than traditional way which consumes more time and money. It is encouraged the effective use of function in the multi-drop system platforms.