Remote diagnosis system for numerical control apparatus

A remote diagnosis system for a numerical control apparatus which is capable of diagnosing the operation state of said numerical control apparatus by means of a terminal unit disposed away from said numerical control apparatus by transmitting image data of said numerical control apparatus from a diagnosis data transmitting unit attached thereto to said numerical control apparatus, comprising:

• an image data read out means for reading out image data corresponding to one character in character representation from an image storage means bearing said image data, said image data including a number of dots which are in a first state;
• and
• a character coding means for counting the number of dots in said image data which are in said first state, and for comparing said image data with reference dot pattern data which have been initially indexed based on said number of dots in said first state and dot patterns in specific rasters of said image data, and for converting said image data into character code when said image data coincides with said reference dot pattern data and for generating a graphic code when said image data fails to coincide with said reference dot pattern data.