IO Field with Error Value | Custom Web Control | WinCC Unified & V8

Custom Web Control

About IO Field with Error Value

IO Field with Error Value is a Custom Web Control for WinCC Unified (TIA Portal) and WinCC V8. It displays a process value in an IO field and replaces it with a red cross and a message when the value matches a defined error value. Operators see at a glance when a measurement is invalid or unavailable, instead of reading a misleading number.

Key Features

• Error detection: processValue is compared with errorValue within errorTolerance, and the field switches to the error state automatically.
• Clear error indication: A red cross symbol with the errorText message replaces the number, so the state never depends on colour alone.
• Operator entry: In InputOutput mode, confirmed entries are checked against minValue and maxValue, then written back to processValue.
• Consistent updates: Tag updates and the setValue method apply the same error detection.

Customization

Set the value format with unit and decimals, and position the value with alignment and verticalAlignment. Typography is controlled by fontFamily, fontSize, fontStyle, fontUnderline and fontStrikethrough, where a fontSize of 0 scales the value with the control height. Colours are set with backgroundColor, borderColor and textColor, while showBackground and showBorder control the container and frame. The fieldLabel and errorLabel properties provide accessible labels, and rangeTooltipText sets the input range hint.

Use Cases

Ideal for tank level and flow displays where sensors may report a fault value, analogue inputs with a known failure code, control room overviews, and operator panels where invalid data must never be mistaken for a real reading. Use Output mode for read-only process values.

Compatibility

Works with WinCC Unified (TIA Portal) and WinCC V8. It uses only offline system fonts and inline graphics, so no external services are required.

TIA Portal Reminder: Clear the Read only option in TIA Portal for any tag linked to processValue that the control must write. Otherwise the control can read the HMI tag but cannot write the operator entry back.

AI-Generated: This custom web control was automatically generated using AI. Test and validate it thoroughly before deploying in production environments.

⚠️ AI-Generated: This custom web control was automatically generated using AI technology. It may contain errors or unexpected behavior. Users are responsible for testing and validating before using in production environments.

## Current version: v1 (2026-10-26)