Epec Programming and Libraries Manual
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Supported platforms: CODESYS 3.5, CODESYS 3.5 SAFETY

 

S_ValidateAI (FB)

Description

This function block validates an analog value by comparing two analog signals. The signals must be of same type and scaling.

Values can be any numeric value. The channel 2 value can be inverted.

 

This function block can validate any numeric value (quantity), not only voltage, current or resistance.

 

Initialization

Init method is used to initialize the necessary static calculation parameters for the function block instance.

The method shall be called at least once before the actual function block can be called, i.e. at the application initialization phase.

The method checks the validity of input parameters. However, none of the function block outputs are affected by the initialization.

 

A parameter error is diagnosed if:

• Init method is not called before the main FB call OR

• i_pEventCode = 0 OR

• i_pEventCodeCh2 = 0 OR

• S_i_Tolerance is out of range

 

 

Initialization parameters (V1.0.0.7)Initialization parameters (V1.0.0.7)

Parameter

Data type

Unit

Range

Description

S_i_InvertedCh2

SAFEBOOL

-

-

Input channel 2 is inverted.

S_i_SafeOutputValue

SAFEDINT

-

-

Safe output value in case of error.

S_i_DiagnosticDelay

SAFEUINT

ms

-

Delay time for diagnostics.

S_i_Tolerance

SAFEDINT

‰

0 – 1000

Tolerance for error diagnostics.

S_i_SumValue

SAFEDINT

same as channel value’s

Sum value of channels, used when channel 2 is inverted.

i_pEventCode

POINTER TO EventCode

-

≠0

Pointer to application variable which is type EventCode. Used with POUs that handle signal data.

i_pEventCodeCh2

POINTER TO EventCode

-

≠0

Pointer to application variable which is type EventCode. Used with POUs that handle validation signal data.


 

Initialization parameters (V1.0.1.0)Initialization parameters (V1.0.1.0)

Parameter

Data type

Unit

Range

Description

S_i_InvertedCh2

SAFEBOOL

-

-

Input channel 2 is inverted.

S_i_SafeOutputValue

SAFEDINT

-

-

Safe output value in case of error.

S_i_DiagnosticDelay

SAFEUINT

ms

-

Delay time for diagnostics.

S_i_Tolerance

SAFEDINT

‰

0 – 1000

Tolerance for error diagnostics.

S_i_SumValue

SAFEDINT

same as channel value’s


Sum value of channels, used when channel 2 is inverted.

S_i_ReferenceValue

SAFEDINT

same as channel value’s


Reference value for tolerance calculation in redundant mode

i_pEventCode

POINTER TO EventCode

-

≠0

Pointer to application variable which is type EventCode. Used with POUs that handle signal data.

i_pEventCodeCh2

POINTER TO EventCode

-

≠0

Pointer to application variable which is type EventCode. Used with POUs that handle validation signal data.


 


Initialization method return value

TRUE: All initialization parameters ok.

FALSE: Error in initialization parameter(s).

 

Operation (V1.0.0.7)Operation (V1.0.0.7)

This function block has two operation modes: Redundant and inverted.

In redundant mode the S_i_Ch1Value is directly compared to S_i_Ch2Value. The difference is calculated by subtracting the smaller value from the larger. The tolerance value is per mil of channel 1 value. If the difference value is smaller or equal to the tolerance value, and no error has occurred, the signal is considered as valid and S_i_Ch1Value is written to S_o_Output.


In inverted mode, the sum of S_i_Ch1Value and S_i_Ch2Value is compared to S_i_SumValue. If the sum values are within given tolerance and no error has occurred, the signal is considered as valid and S_i_Ch1Value is written to S_o_Output.


The block sets o_Status.OutputValid state TRUE if signals are valid and operation is enabled, i.e. i_Enable is TRUE

 

Operation (V1.0.1.0)Operation (V1.0.1.0)

This function block has two operation modes: Redundant and inverted.


In redundant mode the S_i_Ch1Value is directly compared to S_i_Ch2Value. The difference is calculated by subtracting the smaller value from the larger. The tolerance value is per mil of reference value (S_i_Tolerance * S_i_ReferenceValue / 1000). If the difference value is smaller or equal to the tolerance value, and no error has occurred, the signal is considered as valid and S_i_Ch1Value is written to S_o_Output. 


In inverted mode, the sum of S_i_Ch1Value and S_i_Ch2Value is compared to S_i_SumValue. If the sum values are within given tolerance and no error has occurred, the signal is considered as valid and S_i_Ch1Value is written to S_o_Output.


The block sets o_Status.OutputValid state TRUE if signals are valid and operation is enabled, i.e. i_Enable is TRUE

Operation in fault situations

If channel states mismatch continuously over S_i_DiagnosticDelay time, then

• S_o_Output is set to given safe value,

• Status o_Status.OutputValid is set FALSE,

• The corresponding Error bit in o_Status variable is set TRUE, and

• The corresponding EventID is set to i_pEventCode

 

All FB statuses, including errors are reset on rising edge of i_Enable.

 

Inputs

Input variable name

Data type

Range

Description

i_Enable

BOOL

-

Enables validation functionality

S_i_Ch1State

SAFEDINT

See description

Input channel 1 (signal) value

S_i_Ch2State

SAFEDINT

Same as channel 1 value’s

Input channel 2 (validation) value

Outputs

Output variable name

Data type

Range

Description

S_o_Output

SAFEDINT

Same as channel 1 value’s

Validated value.

o_Status

Status

-

Status of output value. See Status structure.

Error diagnostic

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

 

Conditions

S_o_Output value

o_Status. OutputValid

o_Status error status

Event code FunctionID

Event code EventID

i_Enable TRUE

AND

init parameter error AND

 i_pEventCode valid

S_i_Safe OutputValue

FALSE

ParameterError

VALIDATE_AI

PARAMETER_ERROR

i_Enable TRUE

AND

init parameter error AND
i_pEventCode NULL

S_i_Safe OutputValue

FALSE

ParameterError

-

-

i_Enable rises

AND

 init parameters ok AND

inputs match

S_i_Ch1Value

TRUE

-

NO_FUNC

NO_ERROR

i_Enable TRUE

AND

 init parameters ok AND

inputs mismatch

S_i_Safe OutputValue

FALSE

ValueMismatch

VALIDATE_AI

DATA_MISMATCH

 

Example code

Validation code is NOT generated by MultiTool Creator.

The S_ADCToVoltageOrCurrent POUs are included in code template.

 

See examples from How-To Guides (links below)

 

 

Example architecture

When using same type of sensors (equal resistance, current etc.): Validation can be done before sensor function block.

 

For more diversity, different sensors can also be used. For example, using PT and KTY, validation must be done using temperature values.

 

 

 

See also

 

 

Source file topic100386.htm

Last updated 13-Jun-2024