Marks the start of a group of commands.
These servos are often used in humanoid robots and given the number of servos involved and time taken to update them all then you may notice each servo moving one after the other.
This command allows you to mark the start of a group of commands and would normally be placed at the start of your appControl loop. The commands are sent out to the servos in the main loop but they are only acted upon when the end() command is received at the end of your main loop.
Assuming you have called the driver 'ax12_driver' and the servos 'servo1', 'servo2' etc then you can force the servos to update their new movement simultaneously as follows:-