Numerical control machine tool

A numerical control system which is equipped to perform at least one of M, S and T functions, comprising:

• a numerical controller having a code transmission means for combining a numeric code following an address character indicating one of the M, S and T functions with a redundant signal for checking the validity of the numeric code;
• a plurality of transmission lines for conveying the numeric code with the redundant signal from the numerical controller;
• a machine tool connected to said transmission lines, said machine tool having a code reception and identification means for receiving the signal from the code transmission means, said code reception and identification means including means for checking the validity of the received signal based on the numeric code indicating one of the M, S and T functions and the validity checking redundant signal;
• and
• decoding means for decoding the numeric code and providing it to a heavy current circuit of the machine tool in response to the numeric code being determined valid and for generating an alarm signal to keep the machine tool out of operation in response to the numeric code being determined invalid.