The Dynamixel Servos are smart, high performance networked actuators for high end robotics applications. These servos are manufactured by a Korean company called ROBOTIS (http://en.robotis.com/). These servos are very popular among robotics enthusiasts because they can provide excellent position and torque control, and also provide variety of feedback, such as position, speed, temperature, voltage, and so on.

One of their useful features is that they can be networked as a daisy chain manner. This feature is very useful in multijoint systems such as a robotic arm, humanoid robots, robotic snakes, and such others.

The servos can be directly connected to PCs using a USB to Dynamixel controller, which is provided from ROBOTIS. This controller has a USB interface and when it is plugged into the PC, it acts as a virtual COM port. We can send data to this port and internally it will convert the RS 232 protocol to TTL (Transistor-Transistor Logic) and in RS 485 standards. The Dynamixel can be powered and connect the USB to dynamixel controller to start working with it. Dynamixel servos support both TTL and RS 485 level standards. The following figure shows the Dynamixel servos called MX-106 and USB To Dynamixel controller.

There are different series of Dynamixel available in the market. Some of the series are MX - 28, 64 and 106, RX - 28,64, 106, and so on. The following is the connection diagram of Dynamixel, USB to Dynamixel to PC:

The Dynamixel can be connected as daisy chain, as shown in the preceding figure. Each Dynamixel has a firmware setting inside its controller. We can assign the ID of servo, the joint limits, the position limits, the position commands, the PID values, the voltage limits, and so on, inside the controller. There are ROS drivers and controllers for Dynamixel which are available at: http://wiki.ros.org/dynamixel_motor.