Analysis of the problem of requiring the program to be re downloaded during on-site debugging of Online Change

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On-site debugging, where engineers modify code while the equipment is in production and operation.This is an occasion where downtime and material costs are significant.

Test content

1 The number of OnlineChange or the impact of code changes

2 How to shorten the compilation and download time of OnlineChange

3 How to avoid recompiling and redownloading

3.1 The role of TwinCAT 2's .ci and .ri files

Recommended operation habits to avoid downtime caused by program download

4 The possibility of downtime caused by Online Change

1. The number of Online Changes or the impact of code changes

This test did not find any limitations on the number of Online Changes or the amount of code changes, such as what modifications were made, that would require a program to be re-downloaded.

When the CPU utilization is above 75%, these Online Change operations still cannot trigger the The programhas changed!issue.This includes modifying individual numbers, adding several lines of code, adding variables, adding arrays, and even adding function blocks.

Due to various tests not being able to reproduce the issue, the source code of another PLC was imported on top of the original Pro.After compiling, Login prompted to load the program.The alarm code was 1302, due to referencing a library that had not been referenced in the controller previously, requiring the download of the complete project.

2 How to shorten the compilation and download time during Online Change

Usually, the code only requires small changes, but if the program is slightly larger, it will take time to compile and prepare symbols before downloading. Modifying the TwinCAT option in the Project Option can shorten this time:

 


Change the default Symbol download option from Dynamic Symbols to Static Symbols, and uncheck all the ticked options.In order not to affect other devices communicating with PLC, the default settings can be restored when the first download and final debugging are completed.

3. How to avoid downtime caused by program re-downloading

3.1 The role of TwinCAT 2's .ci and .ri files

This test found a correlation between the intermediate files.ri and.ci and the recompilation and download issues of the program.The preferred timing of the generation and refreshing of the TwinCAT 2.ci and.ri files, as well as their respective roles.

 

Therefore, the basic principle for avoiding program download alarms is to maintain the mutual matching of .pro, .ci, .ri, and TCPLC_P_x.wbp.

3.2 Recommended operating habits to avoid downtime caused by program downloads

Usually, the code and path in the controller will not change, only the files on the programming computer side will change.For backup purposes, renaming, saving as, and debugging on a different computer are all possible.When logging in again, a warning may appear saying "The program has changed! Download the program?".If you choose to download, the PLC program will definitely stop, and if you choose not to download, you will not be able to log in to continue debugging.

To avoid this problem, the recommended operation is as follows:

When making backups during on-site debugging, do not use Save As, but instead copy the current file and rename the backup by date.This is to ensure that all intermediate files remain available.

When changing computers or debugging, it is necessary to copy the entire folder, especially the.pro, .ci, and.ri files.

When archiving a project, the .pro, .ci, .ri, and TCPLC_P_x.wbp files should be consistently kept in the latest version.The recommended practice is to perform the following steps before finishing the work: Login - Create Boot Project - Save.Then, back up the entire project folder on the programming PC;also back up the entire \TwinCAT\Boot folder on the controller.

4 The possibility of downtime caused by Online Change

Previously, a customer reported that when debugging on-site, changing a small amount of code in Online Change would cause the PLC to stop, while the CPU configuration was low and the CPU utilization was high.In order to further analyze the cause of this issue, please confirm the following three points when reporting such issues based on the previous description:

Confirm that the PLC program on the programming computer has not been renamed or relocated, and that the ri and ci files have not been moved or deleted;

Confirm that TwinCAT has been set to Static Symbol in Project| Option of TwinCAT PLC Control and uncheck all Global and Local options;

Switch to another computer and retry the operation to rule out any problems with the programming computer itself

If the problem persists, please provide CPU utilization and controller model and report the issue to Beckhoff engineers.