Remote debugging of C# code

Works for PLCnext Control devices running firmware 2023.0 LTS or newer -
for former firmware see Remote debugging pre-2023

Because PLCnext Technology includes an implementation of eCLR, you have the option to establish a C# remote session on a PLCnext Control.

This topic describes the basic steps needed for setting up a remote debug session and establishing a direct connection to a running application by means of Microsoft Visual Studio®. 

Prerequisites

• Microsoft® Visual Studio® 2019 and 2022
• PLCnext Toolchain C# extension for Visual Studio, version 2023.0 LTS
• PLCnext Engineer 2023.0 LTS or newer

What should be done before:

• A C# project for PLCnext Technology prepared in Visual Studio® as shown in Creating a C# firmware library
• The resulting library has been imported into PLCnext Engineer 

How to debug

1. Activate debug mode

   • Connect PLCnext Engineer to the controller.
   • In the PLANT area, right-click on the controller.
   • In the context menu, select Debug On/Off:
     

2. Attach Visual Studio to the process

   • In Visual Studio® open the Debug → Attach to Process... menu.
   • From the Transport drop-down list, select the PLCnext Device entry.
   • From the Connection target drop-down list, select the <Current_Controller_IP>:41101 (Last PlcNext Engineer connect) entry. This will take the settings of your last debug session with the PLCnext Engineer and a PLCnext Control.
     If you configuration does not work or has changed recently, you can update it as following:
     • Click on the Find... button.
     • In the Attach to PLCnext Device dialog that opens, click Load to get the settings of a recent PLCnext Engineer connection to the controller.
     • Press OK to accept the automatically set IP address and path to the image file.
   • If this doesn't work either, you can still set the IP address and port, as well as the path to the binary image manually: 
     • Enter the IP address of the controller and port number (by default: 192.168.1.10:41100).
     • Select the *.img binary image under the following path:
       C:\users\Public\Documents\PLCnext Engineer\Version\Binaries\PROJECT1@binary\eCLR\
       
     • Choose the image currently running on the controller.
     • Confirm your selection with OK.
   • Set set IP address with port and the path for the binary image and click the Attach button.
   • In case the need for authentication on the device is activated you will be asked for credentials before Login. 
   • In Visual Studio®, add breakpoints and execute the code.
     ↪ Execution of the code will stop at the first breakpoint.
   • Evaluate the current variable values:

     

   • Use the functions in the Visual Studio toolbar to jump to the next breakpoint or continue processing of the code:

     
     Alternatively you can also use the debugging controls in PLCnext Engineer.  

1. Make changes to the code while debugging

   • In Visual Studio, choose Debug → Stop debugging from the menu.
   • Make changes to the code and save them.
   • Recompile the project; to do so, open the Build → Rebuild menu and choose your project.
   • Then, switch to PLCnext Engineer, which will already have recognized the changes and prompts you to save the project.
     Note: If the inputs/outputs have been changed in the code, errors might occur in PLCnext Engineer. If necessary, correct them in PLCnext Engineer, too.
   • Write and start the changed project to the controller.
   • In Visual Studio® use Debug → Reattach to Process... to reconnect Visual Studio®, enter your credentials if necessary and continue debugging your code.