This page will demonstrate how to translate a Gerber RS274D File to RS274X. RS274X files contain aperture definitions within the file. But, 274D files need to have the aperture definitions entered manually. Say you've received a file and you're not sure if it's 274D or 274X. Let's examine the difference between these two files first. Take the file you're unsure about, (for this demo we'll use the file called 272p-l1), and drag it into NotePad to open it. (See Below)

Here is our example file. Notice the D-Codes (highlighted), and the series of X,Y coordinates. However, next to the D-Codes there is no aperture information. Therefore, we can deduct that it is a RS274D file.

Below is another file we've opened in NotePad. Notice that this file has D-Codes with an aperture definition following it (highlighted). It also has a series of X,Y coordinates. Since the aperture info is included in the file, we can conclude that this is a RS274X file.

Now we'll start GBRVU and open our RS274D file comp.gbr.
After selecting the file, you will be asked to select an aperture file. We will have to create a new aperture file that is compatible with our Gerber View.
Let's type pcboard.apt for the file name. GBRVU will tell you that the file doesn't exist and will create it for you.

GBRVU will ask you to define a few parameters such as the Format of the Gerber data and Units. You should be able to get this information from the aperture file supplied with the Gerber file. If we look at the file pcboard.apr in notepad, we can see the values of these parameters as well as the size and shapes of the apertures. We will need to enter these to the aperture menu a little later.

GBRVU will report that it found apertures in the Gerber file that are not defined in the aperture file pcboard.apt - that is expected since we need to enter the aperture definitions to pcboard.apt.
To do so, from Gerber viewer's graphic screen click on the
File pull down menu and then click on Apertures.
The aperture menu will come up and at this point we need to enter the shape and size of the un-defined apertures (button pushed up).
Once done, click ok and you should be able to see the Gerber data correctly.

At this point you are ready to export a RS274X file.
To do so, from GBRVU click on the
File pull down menu and then click on Export.
Select your RS274X output file name (which should be different that the input file), and hit OK..