| 摘要 |
PROBLEM TO BE SOLVED: To provide a master device that can maintain a necessary data transmission/reception period without unnecessarily increasing costs required for taking a countermeasure to noise received during a serial communication for transmission and reception of data to and from a slave device via the serial communication and a limitation of a length of a cable to be used in the serial communication.SOLUTION: When the number k of inverters 8-1, ..., 8-k corresponding to motors 5-1, ..., 5-k connected to a smoothing capacitor 3 is less than the maximum number n of inverters 8-1, ..., 8-k corresponding to the maximum number n of connectable motors and is equal to or small than a number N of one or more, a communication rate change determination part 9d' changes a data communication rate from a first communication rate to a second communication rate lower than the first communication rate. The number N is preliminarily set as a threshold value for determining whether the data communication rate is changed from the first communication rate to the second communication rate or not. |
