This part is concerned with the communication between the manipulator and the workstation used to control it. Basically, we have three D/A lines that transmit the required torque (or voltage) from the workstation to the three manipulator's actuators, and we have six A/D lines that transmit the sensors readings at each joint to the workstation (three for the position, and three for the velocity). These readings are used in the controller for feedback information.
A microcontroller system (the MC68HC11EVBU - Universal Evaluation Board) was used. It has a microcontroller, an 8-channel A/D, an RS-232 compatible terminal I/O port, and some wire wrap area for additional circuitry like the D/A unit. The MC68HC11E9 is a high-speed, low-power chip with a multiplexed bus capable of running at up to 3 MHz. Its fully static design allows it to operate at very low frequencies.