Why do G codes seem so complicated? It does not have to be. . . . . .

M & G codes, sometimes simply known as G codes, are the most popular command codes designed to handle numerically controlled (NC) machines used all over the world for manufacturing. Electronics Industry Association proposed a standard for a numeric control program for NC machines in the early 1960’s. It was approved as standard RS-274D in the year 1980.

The original standard dealt with mainframe computers generating punched paper tape. The tapes were presented to a paper tape reader attached to NC machine. Tapes were punched with G codes and the machine followed the G codes to create parts out of raw materials.

The NIST (National Institute of Standards and Technology), a government agency of USA, adopted a variation of RS-274D called RS-274NGC for the Next Generation Controllers.

Solustan, Inc. went one step further to develop a solution with a simple user interface with user’s convenience in mind. It is a multi- purpose utility. It is called LinkCAM or LinkMotion for M&G codes.


1. Simple basics

First of all, let us understand some of the basics of the CNC lingo.

3D G codes – Sophisticated CAM programs generate 3D G codes to manage the movement of all three axis simultaneously to produce and cut out complicated shapes. To understand, design, and produce 3D output require training and understanding of the machinery, software, as well as the job at hand.

2.5D G codes – These G codes do manage all three axis. However, Z is in a fix position while X and Y are moving and vice versa. This is useful for simple cutting of the material to shapes, engraving, and other similar applications. Bring the tool to the surface of the material and continue to move into the material at a careful speed. Once the desired depth is achieved, keep the depth stationery and start moving X and Y axis in a coordinated fashion to achieve desired cut of the material. If the material is dense and depth is more than what a tool can handle comfortably, it is necessary to achieve the depth in multiple passes.

NC machine – numerically controlled machine

CNC – Computerized Numerically Controlled machine

Relative codes – All the codes are computed with dimensions relative to the values of the previous point. This method was popular and necessary when the computers were not very powerful. If an error is introduced during the machine operation, it will stay with the rest of the job.

Absolute codes – This is a better method to generate G codes and easily possible with today/s computers. Absolute positioning will allow recovering of the error during the manufacturing process.

G codes are typically motion commands.

M codes are typically I/O commands and program control commands.

There are many nuances of the CNC process. However, the above terms are sufficient to appreciate this article. Hopefully, this article will help you to plan your next acquisition of machinery to meet your needs.


2How is it done?

One of the basic question people ask is – We know programs like Corel Draw and AutoCAD. Corel Draw type graphic programs are easier to learn, less expensive and allows free form designs. However, these programs create flat files (i.e. Cartesian coordinates with X and Y axis) and have no control over tool moving up and down to perform cutting and/or operations. How do you achieve it with LinkMotion?

This is a very good question. The LinkMotion driver is provided in two parts. One part is a driver just like a printer driver. The other part is an applet that resides in the systems tray. The applet allows the settings of various parameters like feedrate, tool surfacing, tool lift and depth, multiple passes, dwell time, I/O’s, etc. The G codes are created with tool controls built into the job-processing file.


3. Generate G codes and save or edit them

LinkCAM or LinkMotion for M&G codes is a Microsoft Windows compatible driver. The driver is compatible with Win 7 32/64 bit, Win XP, and Win 2000.

Design job in one of the many CAD programs or Corel Draw or Adobe Illustrator. Print the job using LinkMotion driver. The action of printing will create G codes. Save the G codes on hard disk for editing and future use including sending the job to a CNC machine for processing.



4. Generate G codes and send them directly to machine

LinkMotion does allow you to customize the creation of G codes including commands like,

G64 for trajectory planning

G81, 82, and 83 for drilling operations

M commands suitable to the controller for I/O controls

Pause commands

G53 through G59.3 commands for start offsets programming

Design your job in one of the many CAD programs or Corel Draw or Adobe Illustrator. Print the job using LinkMotion driver and send the file directly to controller and machine using Windows spooler while connecting via serial, parallel, USB, or Ethernet ports



5. Send existing G code files to machine

User may have previously saved G code files. Also, user may have created 3D G codes in other CAM programs. LinkMotion will allow opening and sending these files to a port of choice where the CNC machine may have been connected to receive jobs.

Go to LinkMotion user interface and select a previously saved G code file from hard disk. Click OPEN the file and it will be sent to your controller and machine using Windows spooler while connecting via serial, parallel, USB, or Ethernet ports




6. Set up your drill patterns and Go

Drilling is one of the most basic but very important operations. Precision drilling helps assemble parts with ease. Printed circuit boards depend on precision drilling. With LinkMotion, it is truly easy.



7. Single click and Cut True Type font character in any language

All over the world, numbers and alphabets are required in local languages for signage and identification. All you need is a TrueType font for the local language. Simply, use the font to create a character in a graphic program for the size required. Generate the G codes with a single click and you are ready to manufacture from wood, plastic, metal, paper, cloth, and other materials.




G codes used to be black magic. There are G code experts who trained themselves to read G code files and visualized the final output from the machine. No need to do that anymore. Design your job in a simple graphic program in actual dimensions and ‘What you see is what you get’.

What should one ask before acquiring a program to create M&G codes?

  • Can I use the design program I know and own it already?
  • Minimum or no learning curve
  • Easy to use and easy to learn
  • No time consuming file transfers and conversions
  • Reasonable pricing and reliable product
  • Can I work with the PC I have?
  • Can I work with the Windows operating system I have?

LinkMotion is not an application that needs learning. It is a Windows compatible driver like a printer driver. It does its magic in the background after you send the job by clicking ‘Print’ command.
For additional understanding, checking out our LinkCAM driver software, and many of its advance features,
Call me at 781-449-7666
Send email at [email protected]
Further explore details of our products on our web site

Dhiren Shah, Director of Operations
Solustan, Inc.

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