FB_VN_ReadImage

Syntax

Definition:

FUNCTION_BLOCK FB_VN_ReadImage
VAR_INPUT
    sFilePath   : STRING;
    ipDestImage : Reference To  ITcVnImage;
    bRead       : BOOL;
    nTimeout    : TIME;
END_VAR
VAR_OUTPUT
    bBusy       : BOOL;
    bError      : BOOL;
    nErrorId    : UDINT;
END_VAR

Inputs

Name	Type	Default	Description
sFilePath	STRING		Full path of the file or relative path to the default image directory on the target pc
ipDestImage	Reference To ITcVnImage		Returns an image with the loaded content
bRead	BOOL		Reading the file is triggered by a rising edge at this input.
nTimeout	TIME	VISION_ADS_TIMEOUT	Indicates the time before the function is cancelled.

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_ReadImage loads an image from a file asynchronously into the PLC.

	Loading of modified images When loading images, the Vision service caches the data internally. Loading changed images is therefore not possible in the standard system. To do this, adjust the cache settings or see the example Serial loading of images into the PLC for an alternative.

Parameter

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

Destination image ^{(return value)}

The loaded image is reachable via the interface pointer ipDestImage following successful reading.

Application

Loading an image from the path C:\TcVision\Image.bmp looks like this, for example:

fbReadImage(
    sFilePath   := 'C:\TcVision\Image.bmp', 
    ipDestImage := ipImageIn,
    bRead       := TRUE,
    nTimeout    := T#500MS);

IF NOT fbReadImage.bBusy AND NOT fbReadImage.bError THEN
    // image is accessible in ipImageIn
END_IF

Related function block: FB_VN_WriteImage for saving images.

Samples

Serial loading of images into the PLC

Required License

TC3 Vision Base

System Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT V3.1. 4024.44 or later	PC or CX (x64) with PL50, e.g. Intel 4-core Atom CPU	Tc3_Vision