FB_VN_ReadCalibrationResult

FB_VN_ReadCalibrationResult 1:

This FB reads calibration results from a json file on the targte pc.

Syntax

Definition:

FUNCTION_BLOCK FB_VN_ReadCalibrationResult
VAR_INPUT
    sFilePath               : STRING;
    aCameraMatrix           : Reference To TcVnMatrix3x3_LREAL;
    aDistortionCoefficients : Reference To TcVnArray8_LREAL;
    aRotationMatrix         : Reference To TcVnMatrix3x3_LREAL;
    aTranslationVector      : Reference To TcVnVector3_LREAL;
    bRead                   : BOOL;
    nTimeout                : TIME;
END_VAR
VAR_OUTPUT
    bBusy                   : BOOL;
    bError                  : BOOL;
    nErrorId                : UDINT;
END_VAR

FB_VN_ReadCalibrationResult 2: Inputs

Name

Type

Default

Description

sFilePath

STRING

 

Full path of the file or relative path to the default directory on the target pc

aCameraMatrix

Reference To TcVnMatrix3x3_LREAL

 

Returns the camera matrix

aDistortionCoefficients

Reference To TcVnArray8_LREAL

 

Returns the distortion coefficients

aRotationMatrix

Reference To TcVnMatrix3x3_LREAL

 

Returns the rotation matrix

aTranslationVector

Reference To TcVnVector3_LREAL

 

Returns the translation vector

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.

FB_VN_ReadCalibrationResult 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_ReadCalibrationResult loads the calibration results from a file asynchronously into the PLC.

FB_VN_ReadCalibrationResult 4:

Loading of changed calibration results.

When loading the calibration results, the vision service caches the data internally. Loading modified results is therefore not possible in the standard system. To do this, adjust the cache settings or see the sample Serial loading of images to the PLC for an alternative.

Parameter

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

Calibration results

The loaded calibration results can be accessed via the following variables after a successful read operation:

// Calibration results
aCameraMatrix            : TcVnMatrix3x3_LREAL;
aDistortionCoefficients  : TcVnArray8_LREAL;
aRotationMatrix          : TcVnMatrix3x3_LREAL;
aTranslationVector       : TcVnVector3_LREAL;

Application

Loading the calibration results from the path C:\TcVision\ CalibrationResult.json looks like this, for example:

fbReadCalibrationResult(
        sFilePath                := 'C:\TcVision\ CalibrationResult.json',
        aCameraMatrix            := aCameraMatrix,
        aDistortionCoefficients  := aDistortionCoefficients,
        aRotationMatrix          := aRotationMatrix,
        aTranslationVector       := aTranslationVector,
        bRead                    := TRUE,
        nTimeout                 := T#500MS);

IF NOT fbReadCalibrationResult.bBusy AND NOT fbReadCalibrationResult.bError THEN
    // calibration results are accessible
END_IF

Related function block: FB_VN_WriteCalibrationResult.

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