I have a problem that keep encountering while using the dynamixel motors of Robotis GP robot kit. I realized that several motors suddenly stops working, and when I went to the RoboPlus Manager I found that some motors are not being detected and some are appearing as unknown, and this problem arose recently as I was using the robot for the past two weeks without any problems, and now several motors are starting to stop working.
Please, see the attached pictures showing the problems that I got. There are three types of problems. The first problem is when a motor appears as unknown, the second one is when a motor is not being detected, and the third problem is when a motor and the microcontroller is not being recognized at all.
First of all, please check all cables are in good condition.
In my case, using USB hub could sometimes cause unstable connection between the controller and PC.
Secondly, try firmware recovery for the controller and Dynamixels that are experiencing trouble.
Corrupted Dynamixel firmware could also cause such issue.