Numerical control apparatus

A numerical control apparatus comprising:

• a numerical controller to generate a command position for a control target;
• a drive controller to be connected to the numerical controller via a first communication unit;
• and
• a signal detector to be connected to the numerical controller via a second communication unit, and connected to the drive controller via a third communication unit, wherein
• the drive controller generates a command controlling a driver connected to the control target such that the control target follows the command position, and generates indicator signal data to be output to the numerical controller via the first communication unit and at the same time to the signal detector via the third communication unit, and
• the numerical controller includes a processor to perform processing of acquiring the indicator signal data as first indicator signal data via the first communication unit and as second indicator signal data via the signal detector and the second communication unit, comparing the first indicator signal data and the second indicator signal data, calculating a communication delay of the second indicator signal data with respect to the first indicator signal data, and determining input time of a measured signal.