Externally extended type programmable controller

An externally extended programmable control system operatively coupled to first and second mechanical units and including a part of a numerical control apparatus, the first and second mechanical units each generating signals in response to respective operations performed by the first and second mechanical units, comprising:

• a main programmable controller (PC) contained in the numerical control apparatus (CNC) and receiving a command from the numerical control apparatus, for generating first control signals for control of the first mechanical unit based on at least one of the command and the signals generated by the first mechanical unit;
• an I/O unit connected to said main PC, for transmitting the first control signals to the first mechanical unit, and for transmitting the signals generated by the first mechanical unit to said main programmable controller;
• an extended PC externally coupled to said main PC, for generating second control signals based on at least one of the command and the signals generated by the second mechanical unit, for control of the second mechanical unit using an independent sequence program;
• and
• communication means for connecting said main PC, said I/O unit, and said extended PC.