I need to implement Modbus Communication both RTU and TCP with STM32F103 Microcontroller. I am new with Modbus. Does Microcontroller needs Firmware Driver to enable Modbus communication? Is it pssible to use any external Chip for UART to Modbus?
MODBUS TCP involves an ethernet interface, STM32F103 doesn't have it. You can either switch to a ST32 with built-in ethernet plus external PHY or use an chip with hardware TCP stack, e.g. from Wiznet. MODBUS RTU is usually implemented in software with standard UART peripherals.
Modbus is a high-level protocol, usually it is implemented using libs (free_modbus etc) or writing library yourself. Hardware parts varies. As FvM wrote, TCP uses an ethernet interface. RTU uses serial connection, it may be uart (never seen that), rs232, rs485 (the latter is a standard way for modbus as it allows long cables and multiple connections). For rs485 there are a lot of chips converting signals to and from uart.
It's possible. It's more complex, as you have to deal with not only modbus pdu, but also with ethernet frames. So you can use ethernet interface IC, again there are a lot of them with different protocols (parallel, spi, i2c etc).