FB_VN_WriteImage

FB_VN_WriteImage 1:

This FB writes an image to the hard drive.

Syntax

Definition:

FUNCTION_BLOCK FB_VN_WriteImage
VAR_INPUT
    ipImage   : Reference To ITcVnImage;
    sFilePath : STRING;
    bWrite    : BOOL;
    nTimeout  : TIME;
END_VAR
VAR_OUTPUT
    bBusy     : BOOL;
    bError    : BOOL;
    nErrorId  : UDINT;
END_VAR

FB_VN_WriteImage 2: Inputs

Name

Type

Default

Description

ipImage

Reference To ITcVnImage

 

The image to write

sFilePath

STRING

 

Full path of the file or relative path to the default directory on the target pc (e.g. only a file name). If the string is empty, a file name will be generated (containing the current time).

bWrite

BOOL

 

Writing the image is triggered by a rising edge at this input.

nTimeout

TIME

VISION_ADS_TIMEOUT

Indicates the time before the function is cancelled.

FB_VN_WriteImage 3: Outputs

Name

Type

Description

bBusy

BOOL

This output remains TRUE until the function block has executed a command, but at the longest for the duration supplied to the 'nTimeout' input. While bBusy = TRUE, no new command will be accepted at the inputs.

bError

BOOL

This output is switched to TRUE as soon as an error occurs during the execution of a command. The command-specific error code is contained in ‘nErrorId’. If the function block has a timeout error, 'bError' is TRUE and 'nErrorId' is 1861 (hexadecimal 0x745). Is reset to FALSE by the execution of a command at the inputs.

nErrorId

UDINT

Contains the ADS error code or the command-specific error code of the last executed command. Is reset to 0 by the execution of a command at the inputs.

Further information

The function block FB_VN_WriteImage saves an image from a file asynchronously into the PLC.

Parameter

Some parameters are described centrally in the section File Access Parameters.

Input image

The format of the input image ipImage must match the file format defined in the file path sFilePath.

FB_VN_WriteImage 4:

Saving on a rising edge of bWrite

The image is copied internally on a rising edge of the write command. Changes to the image in the following cycle thus have no effects. The image transferred at the time of the rising edge of bWrite is always the one that is saved.

File path and format

The file path sFilePath specifies where the input image ipImage is saved and which image format should be used for saving. The image format is automatically recognized on the basis of the file extension. If no file name is specified it is automatically generated and contains the current time. If no file extension (e.g. .jpg) is specified, the extension .bmp and thus the BMP format are automatically used.

The following image formats are supported for saving.

Notice

Possibility of errors

Make sure that the selected image format corresponds to the format of the actual input image. Otherwise, errors may occur or the saved images may be faulty.

Notice

16-bit images

Only the TIF format and the TwinCAT serialization may be used if 16-bit images are to be saved without losses.

Application

Saving an image to the file C:\TcVision\Image.bmp looks like this, for example:

fbWriteImage(
    ipImage     := ipImageRes,
    sFilePath   := 'C:\TcVision\Image.bmp',
    bWrite      := TRUE,
    nTimeout    := T#500MS);

IF NOT fbWriteImage.bBusy AND NOT fbWriteImage.bError THEN
    // ipImageRes was successfully written to given file path.
END_IF

Related function block: FB_VN_ReadImage for loading images.

Samples

Required License

TC3 Vision Base

System Requirements

Development environment

Target platform

PLC libraries to include

TwinCAT V3.1.4024.54 or later

PC or CX (x64) with PL50, e.g. Intel 4-core Atom CPU

Tc3_Vision