What is the D code of Gerber Files?

D code, simply speaking, the first character is "D". There are three D codes in the Gerber files that are used to control the desktop to move along X-Y location.

D01 (D1): Open the shutter and move the desktop to the corresponding X-Y coordinates.

D02 (D2): Close the shutter and move the desktop to the corresponding X-Y coordinates.

D03 (D3): Open the shutter and move the desktop to the corresponding X-Y coordinates. Then quickly open and close the shutter, thus forming an exposure point.

D01 is a command to draw a line; D02 is a command that only moves the desktop without exposing the film. For example, D01 and D02 are like the pen stroke line and the pen holder of movement in the pen-type photoplotter.

D03 is the “flash” command. When the desktop moves, the shutter is closed. When the desktop moves to the corresponding coordinates, the shutter opens and closes immediately – this will leave an image of the aperture on the film. D03 is a very effective command when drawing pads on a printed circuit board.

The D01, D02, and D03 commands always follow their corresponding data, as in the following example:

X0Y0D02*

X450Y330D01*

X455Y300D03*

This data will cause the photoplotter to do the following: close the shutter and move the desktop to the origin; open the shutter and move the desktop to 450,330; (so draw from 0,0 to 450,330.) Close the shutter and move to 455,300, open the shutter and close the shutter.

Aperture mark, D code and D10-D999

Unlike D01, D02, D03, D10 to D999 are data rather than commands, they are marked on the aperture or on the aperture wheel. The early photoplotter used an aperture wheel with 24 holes / groove.

Table 1 is a correspondence table between the optical aperture and the D code of the early photoplotter.

It can be seen that D10 to D19 are arranged in the normal order, followed by D70 and D71, and D20 is ranked 13th. From D20 to D29, the sequence is extended. The aperture number should be 23 when it is D30, but D72 and D73 are inserted before D30. Most optical drawing and CAM software require you to input the information (shape and size) of the aperture according to the D code. A few of software are required to input according to the aperture number (in this case, you need to rearrange according to the corresponding table above).

There’re special D codes between 3 and 9. It is used to represent special line segments such as dotted lines and dash lines. It is rarely used now, that is, it is only used by some obsolete photoplotters.