This paper presents the design of a generic inertial measurement unit (IMU) module for motion capture system. The module consists of 32-bit microcontroller with gyroscope, accelerometer, and magnetometer to provide orientation estimation of human limbs. An orientation estimation algorithm that compensates magnetic distortion is implemented. Our main contribution is on the sensor network which is low cost but high speed. We developed a serial-chain network for sensors interconnection in which UART communication is used. We also consider frame alignment issue in developing human arm motion capture to improve tracking accuracy. A simple frame calibration method is implemented and tested.