CNC Controllers: Six Modes of Operation

   By on August 3, 2018

Welcome to this introduction to CNC Controllers.  Over the years, I’ve trained dozens of machinists, and by the end of this blog I want you to feel more comfortable around CNC precision tooling.  Keep reading as I walk you through all six modes of operation for CNC controllers.

What is a Controller?

The controller on a CNC machine is this box that’s looks like a jumbo jet cockpit.


Let’s examine the 6 modes of operation


While at the CNC machine controller, you may realize your program generated in Solidworks CAM or Camworks needs an updated spindle speed. Edit mode allows me to change the program at the controller. If you have the need to edit a spindle speed, it’s a good practice to update your Tech DataBase in SOLIDWORKS CAM and CAMWorks as well. (I cover that in a different blog so go check it out)


In “Memory” mode the CNC controller runs through the G-code program posted with SOLIDWORKS CAM or CAMWorks. When the machine is in this mode, parts are being made. We can use SOLIDWORKS Inspection to qualify the quality of our parts.


“MDI” mode allows the machinist to input both G and M codes directly into the machine, like a word processor, giving commands to the tool step by step.


Before production can begin, the machine needs to be referenced. Referencing is the process by which the machines encoders are calibrated. Once the machine position is verified, one of these LEDs will illuminate:

mdi mode in cnc

This Fanuc controller will not operate in Memory Mode until the machine is referenced.


Jogging allows turret control by pressing the Feed Direction switch on the operator panel as seen here:

jog mode in cnc

Pressing the button continuously moves the tool along the axis in the selected direction. This mode is also used when the Renishaw tool probe is being used to touch off the tools.


“Handle” mode allows the tool to be moved by rotating the manual Pulse Generator on the operator panel.


The pulse generated by each index can move the tool in .01”, .001” and .0001” increments.


All of the modes will be accessed from the time you post from SOLIDWORKS CAM or CAMWorks to part production. If you have a topic that interest you, add it to the comments and I’ll write a blog to answer your questions.

Want to take your SOLIDWORKS CAM skills to the next level? Sign up for a training! 

Related Products

Browse the TriMech web store for SOLIDWORKS software to design, analyze and manufacture your products on your desktop.

Wes Wolfenbarger

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