A protected variable is a read-only field that prevents users from editing its value during data entry. This is typically used when values are automatically populated from external sources such as PLCs, RS232 devices, or input files.
When to Use Protected Variables
Protected variables are useful when:
- Data is written automatically from an external system
- You want to prevent manual changes to critical values
- The value should be visible but not editable
How to Set a Variable as Protected
In QW Admin:
- Open Maintain Applications
- Open the target application
- Select the variable
- Set the Protected property to True
- Save the application
Important Behavior
- A variable cannot be both Required and Protected
- Enabling one will automatically disable the other
- Protected fields are read-only during data entry but can still be populated by external sources or scripts
Using Views to Override Protection
Protection can be modified at the view level to support different user roles.
For example:
- Operator view → variable is read-only
- Supervisor view → variable can be edited
This allows you to control who can override values without changing the base application configuration.
Key Considerations
- Protected fields are still included in calculations, reports, and charts
- Protection only applies to user input, not system-driven updates
Related Resources
- Using Input Files and Output Files to Set Defaults and Integrate Data
- Connecting Quality Window To External Data Sources
- Capturing data from multiple RS232 devices
- RS232 Real-Time Data Collection with Quality Window SPC Tutorial
- Input/Output Files in Quality Window: Enhancing Data Connectivity Tutorial