TABLE OF CONTENTS The program address G identifies a preparatory command, often called the G code. This address has one and only objective - that is to preset or to prepare the control system to a certain desired condition, or to a certain mode or a state of operation. For example, the address G00 presets a rapid motion mode for the machine tool, the address G81 presets the drilling cycle, etc. The term preparatory command indicates its meaning - a G code will prepare the control to accept the programming instructions following the G code in a specific way.
A one block example will illustrate the purpose of the preparatory commands in the following program entry:
N7 X13.0 Y10.0
Even a casual look at this block shows that the coordinates X13.0Y10.0 relate to the end position of the cutting tool, when the block N7 is executed (i.e., processed by the control). The block does not indicate whether the coordinates are in the absolute or the incremental mode. It does not indicate whether the values are in the English or the metric units. Neither it indicates whether the motion to this specified target position is a rapid motion or a linear motion. If a look at the block cannot establish the meaning of the block contents, neither can the control system. The supplied information in such a block is incomplete, therefore unusable by itself. Some additional instructions for the...
