So now I am writing a python to analyse the timing of request/reply Vin value, to make sure of the requirement of the Enable/Disable of the simplex UART commands using HC126. Though the TXS0102/04 seems to work, but I have no confidence that the OR'ing of output TxD/RxD won't generate other problems. As I mentioned in my (already deleted) answer, I once studied the very expensive Danamixel bus servo but could afford to play with it.

Now I am googling around to see if there is any alternative comparable with LewanSoul but not too expensive, and also have a good documentation. I found the following review and now reading it.

One problem with the Chat Room here is that I am too slow to write a message. Usually I need more than 3 minutes to write and proofread. But my messages become "permanent" and I could no longer correct any spelling or SEMANTIC ERRORS later. This might cause big confusion to future readers.

One workaround is for me to from time to time update my answer, after a milestone in our project, and also warning the future readers that ours is an exploratory project, and that many things discussed in the chat room is simply wrong if not misleading. But of course the future reading can skimmed through our chat record and understand why we did it this way or that way, after WE MADE MISTAKES. In short, we learn by making mistakes and correct them.

Now I have completed the python program to read LX-824HV's Vin value. The program logic is a bit complicated, so I have written a summary for it.

You might like to comment or make counter suggestion for my python program logic. If the test is successful, I will then tidy up and document the program and upload the complete listing here. But there is nothing urgent. So I will slow down now. Cheers.

PS - I might goggle further on serial bus servo. The article I mentioned above is two years old, and it appears that there has not been too much progress in the area. Some 5 years ago I read about the "Open Digital Servo" proposed by SparkFun, but I sadly heard that it was a failure. I guess for now the expensive DynaMixal and cheap HiWonder are still the two serial bus servos that worth our time to invest.