Forgive me, friends, I am guilty of doing a "pretty it up" process after testing code, and -- sadly -- on a few occassions I have introduced a bug doing this. I did with my Dynamixel driver in the sync_write() method.
Attached is an update to the driver and the demo. The demo is the same except that I've added a baud rate table for the bauds supported by Dynamixels. The great thing about using an "soft" UART in the Propeller is that we can run at non-standard rates, hence have virtually zero error is comms (versus standard rates).
I'm presently working on a project and decided to run at 57600 baud -- 1000000 baud resulted in occasional bad packets.