Python字符串含\r\n写入Ignition SCADA标签后无法换行的问题

I’ve run into this exact issue before—let’s break down what’s happening and how to fix it:

Common Causes & Fixes #

1. The Tag Browser Is Hiding Line Breaks #

The most likely reason you’re seeing spaces instead of line breaks is that you’re checking the tag value in Ignition’s Tag Browser. The browser replaces newline characters (\n or \r\n) with spaces to keep the display compact, but the actual string stored in the tag still has the line breaks intact.

How to Confirm:
Run this quick script to read the tag and print its raw value (this will show you exactly what’s stored):

tag_value = system.tag.read('myStrTag').value
print(repr(tag_value))  # Outputs raw characters, including \r\n if present

If you see \r\n in the output, the tag is working correctly—you just need to display the string properly.

2. Your UI Component Isn’t Set Up for Multi-Line Text #

If you’re displaying the tag in a UI component (like a Label or Text Field), it might not be configured to render line breaks:

• Label: Turn on the Wrap Text property, and set Vertical Alignment to Top so lines stack as expected.
• Text Field: Swap it for a Multi-Line Text Area—single-line text fields automatically strip line breaks.
• Other Components: Double-check the component’s properties for settings related to text wrapping or multi-line support.

3. You Might Not Need the Carriage Return (\r) #

Windows uses \r\n for line breaks, but Ignition runs on Java, which recognizes \n (line feed) as the standard newline. Using \r\n isn’t necessarily wrong, but switching to \n can avoid any potential cross-platform oddities.

Revised Code:

myStr = ''
for i in range(1, 10):
    myStr += f'This is line {i}.\n'  # Simplified to \n
resp = system.tag.write('myStrTag', myStr)
print(myStr)

Quick Final Checks #

• Ensure your tag is set to the String data type (other types can mangle text with line breaks).
• Test the tag value in a multi-line component first—don’t rely on the Tag Browser’s display for verifying line breaks.

Content of the question originates from Stack Exchange, question author MikeA