I am using STM32H745 Discovery kit. I was running the example provided for UART but unable to see any message in Serial terminal. Checked on CRO but I am unable to see any data transmitted from TX pin (PB10).

[JPere.13]

I have directly connected the Tx of board to Rx of my computer and Rx of board to Tx of computer through the TTL to USB converter. I also checked the Tx and Rx of the board on DSO but was not able to see any data.

[Tesla DeLorean]

Then perhaps go through the clock, pin and alternate-function (AF) to understand what's happening.

Check schematic, manual, and solder-bridge connections.