Create and download a file from controller using HMI Button

PLCnext Engineer
1

Hello,
I know there are variants of this issue already answered but I cant figure out how to manage mine specifically.
My need is when the user presses a button on the HMI I want my C# Program to overwrite a specific file (“myReport.txt”) in a specific file path and then download that to the device that pressed the button.
My problem though is that when I try to use “File.WriteAllText(filePath, textData);” on the paths mentioned in the previous solutions, then my plc produces an error. Maybe there is a problem with the write permissions?
Also, I do not care if a user with no access can download the file but I do not want to compromise the security of the project solution + C# code that is running on my PLCnext.
Is that possible? Any ideas?
Thank you in advance.

2

Hi.
Am I right in saying that there are two independent issues here?

                              1. Writing a file to the PLC.
                              2. Transferring the file from the PLC to the HMI device.

For the first issue: What path(s) are causing errors? Can you give more details of what the error looks like?
For the second issue: What method are you using to transfer the file to the HMI device?

3

Hello,
I do not think they are independent, because with a valid filePath I can write to the PLC but I do not think that that filePath will be a valid path that can be stored a file to be downloaded.
I used the following filePath because this is the one that was used in the previous answer for the file to be stored to.:
public const string reportFilePath = “/projects/PCWE/Services/Ehmi/ehmi/myReport.txt”; // ../opt/plc/XXX is the base path
That provided the following error:
image.pngIF I use → public const string reportFilePath = myReport.txt"; // ../opt/plc/XXX is the base path THEN the file is created correctly but I do not think that I can use this file path to download it afterwards.
I haven’t yet used a method to transfer the file to the device from which the user clicked the HMI button.
I appreciate the swift answer!

4

Please try without the leading slash, which indicates that the path should start at the root of the directory tree (/), not from the current directory (/opt/plcnext/)

public const string reportFilePath = "projects/PCWE/Services/Ehmi/ehmi/myReport.txt";
5

Alright, I feel embarrassed now, thank you Martin once again.
So, regarding the security issue:
Forum - PLCnext Community PLCnext Technology from Phoenix Contact is a unique, open ecosystem for modern automation that is capable of meeting all the challenges of the IoT world. Does this way of working around the problem cause any security issues regarding my project solution + C# code?

6

No, I don’t think that Oleksandr’s suggestion in that other conversation causes any security issues for the project.