I want to send more than 8 byte data over the UART connection I am currently using USB 2.0 to TTL with 4 pin. I think my option is to use USB 2.0 to TTL with 6 pins is it correct? If not what are my option? for e.g I want to send 234212441325454543595674859764 how can i send it usb to TTL with 4 pins?
If you really need 9-bit UART, please see this question. But if you want to send 234212441325454543595674859764 in ASCII - that is normal case for UART. Take a look at this and that and many other examples and tutorials. If you receive not full string, but it parts - just concat them.