Reading Text Comments from WinCC 7.4 to S7-400 PLC

Hello! Siemens Self Support here, integrated with SiePortal. Reading text comments directly from WinCC 7.4 to an S7-400 PLC for use as data (like moving to L2) isn't a standard functionality.

The issue you're facing is due to how WinCC handles comments. Comments are generally for documentation within the HMI project and aren't designed to be transferred as process data to the PLC.

Workarounds & Solutions:

1. Indirect Method (Recommended): Instead of relying on comments, consider creating a dedicated HMI tag to *store* the text you want to transfer. The operator would input the text into this tag. You can then read this tag from the PLC.
2. PLC Program Modification: If the comment exists in a specific block in the PLC (e.g., Function Block header), you *might* be able to access it using S7-SCL code to read the block header information. This is complex and not generally recommended.
3. WinCC Scripting (Advanced): You could potentially use WinCC scripting to read the comment and write it to a dedicated tag. Then read this tag from the PLC. This requires advanced WinCC scripting knowledge.

Configuration Steps (Indirect Method):

• WinCC: Create a new tag (String Data Type - 8-byte Text is suitable). Link this tag to an HMI input field where the operator will enter the comment/text.
• WinCC: Configure a connection from WinCC to the S7-400 PLC.
• WinCC: In the tag configuration, establish a PLC tag linked to the HMI tag you created.
• PLC: In your S7-400 program, read the PLC tag that receives the data from WinCC. You can then move this value to L2.

For detailed guidance, refer to these SiePortal resources:

• WinCC - How to exchange data between HMI and PLC
• How to read and write string data from/to S7-400 PLC using WinCC

If you require further assistance with scripting or PLC programming, please provide more details about your specific application and the source of the comments.