An active noise cancellation system for use with an assembly includes adjusting the phase of a reference signal an amount that corresponds to a change in phase of the noise within the system. A double-row angular ball bearing having seals is provided in juxtaposition with one end face of the double-row cylindrical roller bearing. When a test current amount and the predetermined frequency dividing amount are provided, the voltage detector again measures the voltage to generate a second reference voltage. The cyclic service transmits and receives data to and from the device periodically in the data linking format according to the memory map and by using the device data area on the IO memory.