I found the following two EE SE forum discussions on serial bus servo Dynamixel, but I found them not very useful. (3) Single wire two-way serial communication - hardware configuration （Dynamixel XL-320）- EESE 2015aug05
https://electronics.stackexchange.com/questions/183410/single-wire-two-way-serial-communication-hardware-configuration

(4) How can I make a half-duplex UART to TTL converter for communicating to a servo (Dynamixel AX-12A) with a HC04 and a HC126? - EESE 2020jul20
https://electronics.stackexchange.com/questions/511349/how-can-i-make-a-half-duplex-uart-to-ttl-converter-for-communicating-to-a-servo. Cheers.