Gerber Format - RS-274-D Standard Gerber

RS-274-D Standard Gerber

Standard Gerber, is largely superseded by extended Gerber. It was created from a subset of the Electronic Industries Association RS-274-D specification, a format to drive mechanical NC machines in a wide range of industries. Be aware that the term RS-274-D is often used incorrectly (with the qualifying "Gerber" postfix omitted) to refer to the standard Gerber subset, rather than the original RS-274-D superset itself. Standard Gerber is used to drive vector photoplotters, which indeed were 2D NC machines. It is a simple ASCII format consisting of commands and X, Y coordinates. An example of a Gerber RS-274-D file:

D11* X1785250Y2173980D02* X1796650Y2177730D01* X1785250Y2181480D01* X1796650Y2184580D02* D12* X3421095Y1407208D02* X3422388Y1406150D01* M02*

RS-274-D was designed in the 1960s and 1970s to drive numerical controlled machines such as vector photoplotters, machines now all replaced by raster-photoplotters. An RS-274-D file on its own is not an image description because it does not contain all information: the coordinate unit and the definitions of the apertures are not defined in the RS-274-D file. (Apertures are the basic shapes, similar to fonts in a PDF file.) The coordinate units and apertures were supposed to be set manually by the plotter operator. They were typically described in a free-format text file, called an aperture file or a wheel file (because the apertures were mounted on a wheel and rotated into the light beam), intended for human reading. There are no standards for wheel files in RS-274-D, so the designer and the plotter operator had to agree on these on a case-by-case basis.

It only supports a few simple imaging operators. To work around this limitation constructions such as "stroking," also known as "painting" or "vector-fill" are needed. Standard Gerber was well-suited to drive vector plotters and was constrained by the technology then available. It was designed for a manual workflow. It is not suitable for fully automated data transfer between PCB designers and manufacturers. PCB manufacturers have to enter coordinate units and aperture definitions manually.

RS-274-D has been deprecated by Ucamco.