Commands

ARX command in AutoCAD : Loads, unloads, and provides information about ObjectARX applications

If you need a clear, step‑by‑step guide to using the arx command in AutoCAD, this article explains what the command does, how to use it, common reasons it may fail and how to fix them, plus alternative loading methods and practical tips for both users and developers.

What is the arx command?

The arx command in AutoCAD is used to load and unload ObjectARX applications (modules built with the ObjectARX C++ SDK, typically with a .arx extension). ObjectARX modules extend AutoCAD with compiled functionality (commands, custom objects, event handlers) that run inside the AutoCAD process.

Key points:

  • ObjectARX = C++/native AutoCAD plug‑ins (usually .arx files).
  • arx provides a way to load, unload and get info about these modules.
  • For other extension types, use commands like APPLOAD or NETLOAD (see Alternatives).

When and why to use arx

Use arx when you need to:

  • Run a feature provided by a third‑party or in‑house ObjectARX plug‑in.
  • Test or debug a compiled AutoCAD module.
  • Load an ARX module for the current session without installing it permanently.

Benefits:

  • Compiled modules can deliver high performance and deep integration with AutoCAD.
  • Useful for developers distributing advanced functionality that cannot be implemented in LISP or .NET.

How to use the arx command (Step by step)

Prerequisites

  • Verify the .arx file was compiled for your AutoCAD version and the correct platform (32‑bit vs 64‑bit).
  • Ensure you have the required file permissions and that your antivirus or security settings are not blocking the file.
  • If you are a developer, ensure dependencies (DLLs) required by the ARX are available.

Step-by-step (command line approach)

  1. Open AutoCAD.
  2. At the command prompt, type arx and press Enter.
  3. Follow the command prompts to load or unload an ARX module. AutoCAD will ask for the file path or present options (depending on your AutoCAD version).
  4. If loading succeeds, the ARX functionality (commands/custom objects) should be immediately available.

Note: Exact prompts and dialogs can vary by AutoCAD release. If you prefer a dialog-based approach, use APPLOAD (see below).

Step-by-step (APPLOAD dialog)

  1. Type APPLOAD at the command prompt and press Enter.
  2. In the Load/Unload Applications dialog, click Contents or Browse.
  3. Select the .arx file and click Load.
  4. Optionally add the module to the Startup Suite to load it automatically at AutoCAD startup.

Example scenario

  • You received plugin.arx from a vendor:
    • Confirm plugin.arx is built for your AutoCAD release.
    • Use APPLOAD → Browse → select plugin.arx → Load.
    • Use the plugin’s documented commands or custom menus provided by the ARX.

Common problems (Why arx doesn’t work) and fixes

Below are frequent causes why an ARX might fail to load, and how to fix them.

  • Version mismatch
    Problem: ARX was compiled for a different AutoCAD release.
    Fix: Obtain or compile a build of the ARX that targets your exact AutoCAD version.

  • 32‑bit vs 64‑bit mismatch
    Problem: Trying to load a 32‑bit ARX into 64‑bit AutoCAD (or vice versa).
    Fix: Use a matching build for the platform or run the correct AutoCAD architecture.

  • Security restrictions (SECURELOAD / Trusted locations)
    Problem: AutoCAD blocks loading unknown or unsigned modules.
    Fix: Add the folder to AutoCAD Trusted Locations (Options > Files > Trusted Locations), or, with caution, adjust the SECURELOAD variable (0 to disable restrictions temporarily). Prefer adding trusted paths rather than disabling security.

  • Blocked by Windows
    Problem: Windows marks downloaded files as blocked.
    Fix: Right‑click the file → Properties → click Unblock (if present) → Apply.

  • Missing dependencies (DLLs or runtime)
    Problem: The ARX relies on other DLLs that aren’t on the system.
    Fix: Install required redistributables and place dependent DLLs in the same folder or a location on the PATH. Use tools like Dependency Walker to inspect missing dependencies.

  • Insufficient privileges
    Problem: AutoCAD cannot access the file due to permissions.
    Fix: Run AutoCAD as an administrator or place the file in a directory with proper access.

  • File corruption
    Problem: The ARX file is corrupted.
    Fix: Reacquire the file from the vendor or rebuild it.

  • Conflicting versions loaded
    Problem: Another module or an older version conflicts with the ARX.
    Fix: Unload conflicting modules or restart AutoCAD and load only the needed module.

Troubleshooting tips:

  • Check AutoCAD’s command window for error messages when loading.
  • Use APPLOAD dialog to see load errors or messages.
  • Restart AutoCAD after installing or changing system settings.

Alternative commands and methods

  • APPLOAD

    • Use to load .arx, .lsp, .fas, .vlx, and more via a dialog. Also lets you add modules to the Startup Suite for automatic loading.

  • NETLOAD

    • Use for loading .NET assemblies (.dll) created with AutoCAD .NET API (C# or VB.NET). Not for native ARX files.

  • Startup Suite / acaddoc.lsp / acad.lsp

    • Use AutoCAD startup mechanisms (Startup Suite in APPLOAD, or LISP files called at startup) to automatically run code or load modules when AutoCAD starts.

  • CUI / Menus

    • Use the CUI (Customize User Interface) to add commands or menu items that call functions provided by ARX modules.

When to use which:

  • Use ARX or APPLOAD for native ObjectARX modules.
  • Use NETLOAD for .NET plug‑ins.
  • Use APPLOAD Startup Suite or script/startup LISP for auto‑loading at startup.

Tips for developers and CAD managers

  • Always build for the exact AutoCAD version and platform.
  • Provide a clear installation guide with dependencies and required privileges.
  • Use digital signing for distributed modules to reduce security warnings.
  • Maintain a versioning policy and keep a folder with tested builds per AutoCAD release.
  • Use logging in your ARX to report load errors (file paths, missing symbols) to assist troubleshooting.
  • For enterprise deployment, use Trusted Locations and group policy to streamline installation while retaining security.

FAQ

How can I check whether an ARX module is currently loaded?

Use the APPLOAD dialog to view loaded modules or check the AutoCAD command window for messages when the module was loaded. Some ARX modules also provide commands (for example, an “About” command) to report status.

Can I use arx to load .NET (.dll) plug‑ins?

No. Use NETLOAD for AutoCAD .NET assemblies (.dll). arx is intended for ObjectARX native modules (.arx).

How do I unload an ARX module?

You can use the arx command or the APPLOAD dialog to unload a module, or restart AutoCAD. Exact unload behavior depends on the module; some ARX modules may not support clean unload if they register persistent objects—restart AutoCAD to ensure complete unload.

What does SECURELOAD do and is it safe to change?

SECURELOAD controls whether AutoCAD enforces loading restrictions for untrusted applications. Lowering it (e.g., to 0) may let modules load but reduces security. Prefer adding trusted folders via Options > Files > Trusted Locations instead of disabling security globally.

What if the ARX file is reported as incompatible?

This typically means a version or architecture mismatch. Obtain an ARX built for your AutoCAD release (and 32/64‑bit architecture), or recompile it with the correct ObjectARX SDK.

How can I make an ARX load automatically when AutoCAD starts?

Add the ARX to the Startup Suite in the APPLOAD dialog or create a startup script (acad.lsp / acaddoc.lsp) that loads the module.

How do I find missing DLL dependencies for an ARX?

Use dependency inspection tools (e.g., Dependency Walker, modern alternatives) on the ARX and any linked DLLs to identify missing runtime libraries.

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