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

SMD aluminum electrolytic capacitor

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

Huaqiang Square crystal original spot stock

During real-world project implementation, certain key data inputs require the operator to confirm potential errors before proceeding. For example:

Figure 1

When a value of "99" is entered into an input/output field and the Enter key is pressed, the system does not immediately update the variable. Instead, a confirmation message box appears. If the user selects "Yes," the new value is applied. If "No" is selected, the original value remains unchanged in the variable. This article explains how to implement this behavior using WinCC's input/output fields.

1. Prerequisites

Create two variables of the same data type: DisplayValue and TempValue. DisplayValue is the actual variable that will be controlled, while TempValue acts as a temporary storage for the user input before it's confirmed.

Figure 2

2. Input/Output Field Property Settings

Create a new input/output field on the screen and open its properties dialog. Navigate to Properties → Output/Input → Output Value. Right-click the dynamic part to access the settings.

Figure 3

Open the dynamic dialog and select the variable you want to control—DisplayValue in this case—and configure the data type accordingly.

Figure 4

3. Input/Output Field Event Settings

3.1 Change Action Settings

Select the same input/output field and open the Properties dialog. Go to Event → Attributes → Output/Input → Input Values, then right-click the Change Actions section.

Figure 5

Open the direct connection dialog. Keep the source as default and connect the target directly to the temporary variable, TempValue.

Figure 6

3.2 Keyboard Release Action Settings

Again, select the same input/output field and open the Properties dialog. Go to Event → Keyboard → Release, and right-click the action part.

Figure 7

Open the C Action Editor and write code that checks if the user has finished entering data and pressed Enter.

Figure 8

The code looks 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) // if user confirms
    {
        SetTagWord("DisplayValue", TempValue); // update the main variable
    }
}

Once the system runs, pressing Enter in the input field triggers the confirmation window shown in Figure 1.

4. Additional Notes

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.