To input a servo coefficient decided by simulation on a personal computer to an estimating board without manual input, and to estimate control.

This common communication board 20 has both a general-purpose interface to the personal computer 10 and a dedicated interface to the estimating board 30, divides variable-length data transmitted from the personal computer 10 into data of eight bits and transmits the individual data to the estimating board 30. The communication board 20 packs up the data of eight bytes transmitted from the estimating board 30 and transmits the packed data to the personal computer 10 as a series of data. Thereby, the servo coefficient can be directly set to the estimating board 30 from the personal computer 10. Characteristic data or the like obtained by the estimating board 30 can be directly taken into the personal computer 10.