Centroid PLC Programming Introduction

Centroid's PLC (Programmable Logic Controller) programming language is the logic engine that drives how machine I/O behaves on Centroid CNC control systems. It is used on all current Centroid platforms, including Oak, Allin1DC, MPU11, Acorn, AcornSix, Hickory, and CNC11/CNC12 controllers, and is the primary way to customize machine logic beyond standard CNC motion and G-code operations.

At its core, the Centroid PLC program continuously monitors inputs (such as switches, sensors, and panel buttons) and drives outputs (relays, indicators, auxiliary functions) based on defined logical conditions. While it may look different from traditional ladder diagrams familiar in industrial PLC systems, each statement in Centroid's language performs a similar role, such as evaluating inputs and setting outputs accordingly.

The language is a simple statement-based logic language with support for logical and arithmetic operators, timers, and variables. It allows machine builders and integrators to encode everything from basic safety interlocks and auxiliary control sequencing to more complex custom features tailored to a specific machine's needs.

Centroid provides stock PLC programs for most common machine configurations that can be compiled and installed as-is, but the PLC language also empowers advanced users to modify or extend those behaviors. Tools like the PLC compiler, diagnostic menus, and real-time logic analyzer ("PLC Detective") are included to help develop, troubleshoot, and fine-tune PLC programs.

Whether you are customizing safety logic, auxiliary equipment control, or special machine cycles, Centroid's PLC programming framework gives you a flexible and powerful way to control I/O and behavior at the heart of the CNC control system.

Click one of the links below for more information!

• What can I do with the Centroid PLC?
• Where can I find Centroid PLC documentation?
• Centroid PLC FAQ
• Centroid PLC Videos
• Need Help with the Centroid PLC?

What can you do with the Centroid PLC?

• You can create your own Centroid CNC Apps!
• Your App will command and control Centroid's CNC12 CNC software.
• You can create simple Apps like the Power Feed example shown in the video below or a more complex App that would completely replace the Centroid UI.
  
  • Its all up to you!
• The Centroid PLC is free, there is no charge to use the Centroid PLC tools themselves!

Where can you find Centroid PLC documentation?

• Centroid PLC documentation is current included with every CNC12 installation.
  
  • Mill: c:\cncm\CentroidAPIDocumentation
  • Lathe: c:\cnct\CentroidAPIDocumentation
  • Router: c:\cncr\CentroidAPIDocumentation
  • Plasma: c:\cncp\CentroidAPIDocumentation
  
  
  • MillDemo: c:\Centroid_Mill_Intercon_Offline\CentroidAPIDocumentation
  • LatheDemo: c:\Centroid_Lathe_Intercon_Offline\CentroidAPIDocumentation
• Also available online!
  • https://centroidcnc.com/CentroidAPI/
• Need help?
  • Just make a post on the Centroid API Technical Support Forum

Centroid PLC FAQ

• Q: What is the Centroid CNC API?
• A: The Centroid API (Application Programming Interface), formerly Skinning API, is an easy way to build your own Custom CNC Applications and solutions powered by any of Centroid's CNC Control Boards (Allin1DC, Oak, Hickory, Acorn, and AcornSix).

• Q: What can I do with it?
• A: Use the Centroid API to create your own custom CNC applications that can run along with CNC12 or completely replace the CNC12 UI.
  Your Apps can command motion, control motors, pumps, activate accessories, interface with a robot, read sensors, read inputs, control outputs, run macros, run g codes, display all kinds of machine tool information such as but not limited to: spindle speed, feedrate, WCS and Machine positions. Run probing cycles, set part zeros, interface with 3rd party software. The applications and functions are nearly limitless.

• Q: How much does the Centroid API cost?
• A: The Centroid APi is free and open, there is no charge to use the Centroid APi tools to create your own CNC application. A CNC12 "Pro" License is the recommended minimum software license to use the Centroid API effectively.

• Q: What programming languages can I use to create a Centroid CNC App using the Centroid API?
• A: At this time only Visual Basic.net and C# languages are officially supported however, Console, WinForms, and WPF projects are supported with those languages.

• Q: What programming tools does Centroid use and recommend when creating Apps?
• A: Visual Studio Community Edition (Free) or Visual Studio Pro/Enterprise (Paid), see more here: https://visualstudio.microsoft.com/vs/compare/

• Q: Is there a place I can get help?
• A: Yes, Centroid has created the Centroid API Technical Support Forum where we will answer questions and take suggestions.

• Q: Can I download the Centroid example Apps to edit myself?
• A: Yes, on the CentroidCNC GitHub Repos:
  1. VB: https://github.com/CentroidCNC/CentroidAPI_VBnet_PowerFeed
  2. C#: https://github.com/CentroidCNC/CentroidAPI_CSharp_PowerFeed

• Q: Where is the Centroid CNC12 API documentation?
• A: New CentroidAPI Documentation will be coming soon on the website.
  Current CentroidAPI Documentation is available in your CNC12 Install Directory:
  • Mill: C:\cncm\CentroidAPIDocumentation
  • Lathe: C:\cnct\CentroidAPIDocumentation
  • Router: C:\cncr\CentroidAPIDocumentation
  • Plasma: C:\cncp\CentroidAPIDocumentation
  • MillDemo: C:\Centroid_Mill_Intercon_Offline\CentroidAPIDocumentation
  • LatheDemo: C:\Centroid_Lathe_Intercon_Offline\CentroidAPIDocumentation

• Q: What are the requirements for using the Centroid API?
• A:
  1. Centroid CNC12 Installed (Offline or Standard, but Offline is limited, ie. no jogging or skin_event calls possible)
     - https://centroidcnc.com/centroid_diy/centroid_cnc_software_downloads.html)
  2. Visual Studio Installed
     - https://visualstudio.microsoft.com/vs/compare/
  3. A 64-bit Development PC running Windows 10 or 11
     - https://centroidcnc.com/cnc_pc_performance_requirements.html
     - Note: Must Exceed our Minimum Spec but will vary depending on the scale of your CentroidAPI Application
  4. (Optional but Recommended) A CentroidCNC Control Board
     - https://shopcentroidcnc.com/
     - The Offline CNC12 Mill and Lathe Intercon installer can be used for basic development and testing but is not ideal for complex operations.

• Q: I am inexperienced with programming. What knowledge do I need to have the best chance at success?
• A: You should understand how to reference external assemblies, call into unmanaged or third-party code, and wrap lower-level APIs in higher-level abstractions for use within your application. The Centroid API is not network-based; it operates entirely through method calls exposed by a DLL. As such, familiarity with object models, method invocation patterns, and error/return-code handling is important.
  
  You should also have a basic understanding of concepts such as:
  • Designing wrapper classes or service layers around an external DLL
  • Managing state between calls, especially when calls must be sequenced correctly
  • Handling synchronous operations that may be invoked in rapid succession
  • Identifying and mitigating performance bottlenecks in high-frequency API usage
  • Working with APIs that rely on return codes rather than exceptions

Centroid API Videos

Introduction: Make your own CNC App using the Centroid API

Make your own CNC Applications with the Centroid CNC12 APi, Power Feed App example step-by-step!

Centroid API Help

The primary source of Centroid API tech support and the lastest API Information is the Centroid API Technical Support Forum. Please post any questions you have in this Support Forum so other users can benefit from your questions and our Community's Answers.