Control system

A control system comprising:

• a controller having a serial communication function;
• and
• a plurality of input/output units having a re-clock function, the controller and the input/output units being daisy-chained, wherein each input/output unit includes:
• a phase detection circuit detecting a phase of a rising or falling edge of serial data received through serial communication and outputting a phase difference between the phase of the rising or falling edge of the serial data and a phase of a reference clock as phase difference data;
• a phase determination circuit determining whether the phase difference data output from the phase detection circuit exceeds a predetermined range and outputting a determination signal when determined that the phase difference data exceeds the predetermined range;
• and
• a first recording memory unit recording a frequency of the determination signal output by the phase determination circuit, and
• wherein the controller is configured to:
• acquire the frequency of the determination signal of each of the input/output units recorded by the first recording memory unit of the respective input/output unit by the serial communication function;
• specify a noise mixture route based on the acquired frequency of the determination signal of each of the input/output units;
• and
• notify the specified noise mixture route.