Input operation with acknowledgment using WinCC input/output fields - Database & Sql Blog Articles

In real-world applications, certain critical data inputs require the operator to confirm any errors before proceeding. For example, when a value is entered into an input/output field and the Enter key is pressed, the system does not immediately update the variable. Instead, a confirmation dialog appears. If the user clicks "Yes," the new value is applied; if "No" is selected, the original value remains unchanged.

Figure 1

This functionality can be implemented in WinCC using input/output fields. Below is a step-by-step guide on how to set it up.

1. Prerequisites

Create two variables of the same data type: one named DisplayValue, which is the actual variable being controlled, and another named TempValue, used as a temporary storage. These variables will help manage the input process and ensure that changes are only applied after confirmation.

Figure 2

2. Input/Output Field Properties

Add a new input/output field to your screen and open its properties. Navigate to the Output / Input tab, select Output Value, and right-click on the dynamic part to open the dynamic configuration dialog.

Figure 3

Select the variable you want to control, such as DisplayValue, and configure the data type accordingly.

Figure 4

3. Event Settings for Input/Output Fields

3.1 Change Action Settings

Go to the Event section, then Attributes > Output / Input > Input Values. Right-click on the Change Actions section and set up a direct connection to the temporary variable TempValue.

Figure 5

Figure 6

3.2 Keyboard Release Action Settings

Open the Event menu again, go to Keyboard > Release, and right-click on the action area to open the C Action Editor.

Figure 7

Write code to detect when the Enter key is pressed. This will trigger a confirmation message box.

Figure 8

The code might look like this:

  Int TempValue = GetTagWord("TempValue");
  Char szBuffer[20];
  Sprintf(szBuffer, "Input number: %d", TempValue);
  If (nChar == 13) // if Enter key is pressed
  {
      Int xRet = MessageBox(NULL, szBuffer, "Confirmation Window", MB_YESNO | MB_ICONQUESTION | MB_SYSTEMMODAL);
      If (xRet == IDYES)
      {
          SetTagWord("DisplayValue", TempValue); // apply the new value
      }
  }
  

When the application runs, pressing Enter in the input field will bring up the confirmation window shown in Figure 1, ensuring the operator reviews the input before it's applied.

4. Additional Information

This setup was tested on Windows XP Professional SP2 with WinCC V7.0 SP1 ASIA. For more details about the MessageBox function, refer to Microsoft’s official documentation.