S_ValidateAccessCode (FUN)

Epec Programming and Libraries Manual

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Supported platforms: CODESYS 3.5, CODESYS 3.5 SAFETY, CODESYS 3.5 SP19 SAFETY

S_ValidateAccessCode (FUN)

Description

This function checks if given response code match with challenge code.

Multitool Creator code template includes access code validation automatically.

This function is endianness-aware, but given response code must be already in big-endian format.

The response code is compared to big-endian result of CalculateAccessCode.

Operation

The function calculates checksum using CalculateAccessCode function. The calculated sum is compared to given i_ResponseCode. If the codes match, output value o_OutputValid is set TRUE, and error code is not added to the pointed EventCode.

Inputs

Input variable name	Data type	Range	Description
i_ChallengeCode	WORD	-	Challenge code to be compared.
i_ResponseCode	WORD	-	Response code to be compared.
i_ProjectKey	STRING(80)	-	Data for code encryption.
i_pEventCode	POINTER TO EventCode	≠ 0	Pointer to EventCode variable.

Outputs

Output variable name	Data type	Range	Description
o_OutputValid	BOOL	TRUE/FALSE	Calculated value is valid.
o_ParameterError	BOOL	TRUE/FALSE	Error in input parameters.

Return value

Data type

Description

SAFEBOOL

TRUE = Signature ok

FALSE = Signature mismatch or calculation failure

Error diagnostic

See Diagnostic Interface library description of error status and event code functionality.

Conditions	Return value	o_OutputValid	o_ParameterError	Event code FunctionID	Event code EventID
Length of i_ProjectKey = 0	FALSE	FALSE	TRUE	VALIDATE_ ACCESS_CODE	PARAMETER_ERROR
i_pEventCode = 0	FALSE	FALSE	TRUE	-	-
parameters ok AND response code match with encrypted challenge code	TRUE	TRUE	FALSE	NO_FUNC	NO_ERROR
parameters ok AND response code mismatch with encrypted challenge code	FALSE	TRUE	FALSE	VALIDATE_ ACCESS_CODE	DATA_MISMATCH

Example code

Non-safe Definitions:

(* Challenge code and response mapped to OD *)

(* 16#21FE Challenge code for safety parameter editing *)

ChallengeCode : WORD := WORD#0;

(* 16#21FF Response code for safety parameter editing *)

ResponseCode : WORD := WORD#0;

Safe definitions:

S_ValidationOk : SAFEBOOL:=FALSE;

ParameterError: BOOL;

OutputValid: BOOL;

EC_ValidateAccessCode:EPEC_DITF.EventCode;

Init at safe PRG:

EC_ValidateAccessCode.DeviceID := 16#C0;

EC_ValidateAccessCode.ChannelID := BYTE#0;

EC_ValidateAccessCode.FunctionID := EPEC_DITF.FunctionIDs.VALIDATE_ACCESS_CODE;

EC_ValidateAccessCode.EventID := EPEC_DITF.ErrorIDs.NO_ERROR;

Code at safe PRG:

S_ValidationOk:=S_ValidateAccessCode(

i_ChallengeCode:=ChallengeCode,

i_ResponseCode:=ResponseCode,

i_ProjectKey:='MyProjectKey',

i_pEventCode:=ADR(EC_ValidateAccessCode),

o_ParameterError => ParameterError,

o_OutputValid => OutputValid

);