FB_VN_FileSourceControl

 Methods

Further information

The function block FB_VN_FileSourceControl can control File Source instances with the full range of functions in the PLC. Alternatively, this is also possible with limited functionality with the function block FB_VN_SimpleCameraControl.

State machine

The following diagram shows the state machine. The main states are marked in blue, the transition states are gray and the error state is red.

The following methods can be used to control the state machine:

• GetState
• StartAcquisition
• StopAcquisition
• TriggerImage
• TriggerImageByName
• Reset

If a method is called in a state for which it is not intended, the error code INVALIDSTATE (16#712) is returned.

Application with continuous image acquisition

A state machine that continuously retrieves received images looks like this, for example:

VAR
    fbFileSource    :   FB_VN_FileSourceControl;
    eState          :   ETcVnCameraState;
    ipImageIn       :   ITcVnImage;
    ipImageInDisp   :   ITcVnDisplayableImage;
    hr              :   HRESULT;
    nNewImageCounter:   UINT;
END_VAR

eState := fbFileSource.GetState();

CASE eState OF

TCVN_CS_INITIAL, TCVN_CS_OPENING, TCVN_CS_OPENED, TCVN_CS_STARTACQUISITION:
    hr := fbFileSource.StartAcquisition();

TCVN_CS_ACQUIRING:
    hr := fbFileSource.GetCurrentImage(ipImageIn);

    // Check if new Image was received
    IF SUCCEEDED(hr) AND ipImageIn <> 0 THEN
        nNewImageCounter := nNewImageCounter + 1;

        // Place to call vision algorithms
        hr := F_VN_TransformIntoDisplayableImage(ipImageIn, ipImageInDisp, hr);
    END_IF

TCVN_CS_ERROR:
    hr := fbFileSource.Reset();

END_CASE

Application with trigger

A state machine that continuously triggers an image with a special file name looks like this, for example:

VAR
    fbFileSource    :   FB_VN_FileSourceControl;
    eState          :   ETcVnCameraState;
    ipImageIn       :   ITcVnImage;
    ipImageInDisp   :   ITcVnDisplayableImage;
    bTrigger        :   BOOL := TRUE; 
    sFileName       :   STRING := 'FileName.bmp';
    hr              :   HRESULT;
    nNewImageCounter:   UINT;
END_VAR

eState := fbFileSource.GetState();

CASE eState OF

TCVN_CS_INITIAL, TCVN_CS_OPENING, TCVN_CS_OPENED, TCVN_CS_STARTACQUISITION:
    hr := fbFileSource.StartAcquisition();
    
TCVN_CS_TRIGGERING:
    hr := fbFileSource.TriggerImage();
    
TCVN_CS_ACQUIRING:

    IF bTrigger THEN
        hr := fbFileSource.TriggerImageByName(sFileName);
        IF SUCCEEDED(hr) THEN
            bTrigger := FALSE;
        END_IF
    ELSE
        hr := fbFileSource.GetCurrentImage(ipImageIn);

        // Check if new Image was received
        IF SUCCEEDED(hr) AND ipImageIn <> 0 THEN
            nNewImageCounter := nNewImageCounter + 1;

            // Trigger next image
            bTrigger := TRUE;

            // Place to call vision algorithms
            hr := F_VN_TransformIntoDisplayableImage(ipImageIn, ipImageInDisp, hr);
        END_IF
    END_IF

TCVN_CS_ERROR:
    hr := fbFileSource.Reset();

END_CASE

As an alternative to the TriggerImageByName(sFileName) method, the TriggerImage() can be used to always get the next image from the File Source Control list.

Samples

• Triggering an image by file name

Related function blocks

Required License

TC3 Vision Base

System Requirements