S_OutputGroupControlAndDiagnostics (FB)

Epec Programming and Libraries Manual

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Supported platforms: CODESYS 3.5 SAFETY

S_OutputGroupControlAndDiagnostics (FB)

Description

This function block monitors supply voltage and diagnoses safety switch faults.

The function block uses internally S_ADCToVoltageOrCurrent to convert ADC values to voltage and validate voltage limits.

Voltage tolerance is validated by library's internal implementation.

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 is not called before the main FB call OR
i_pEventCode = 0 OR
S_i_VoltageLowLimit >= S_i_VoltageHighLimit OR
S_i_VoltageLowLimit < 0 OR
S_i_VoltageHighLimit <= 0 OR
S_i_VoltageHighLimit > VALUE_AT_AD_MAXIMUM.U_SUPPLY OR
S_i_DiagnosticDelay > 100

Parameter	Data type	Unit	Range	Description
S_i_VoltageHighLimit	SAFEDINT	mV	> 0	Limit for overvoltage diagnosis.
S_i_VoltageLowLimit	SAFEDINT	mV	>= 0	Limit for undervoltage diagnosis.
S_i_DiagnosticDelay	SAFEUINT	ms	0 - 100	Delay time for diagnostics.
i_pEventCode	POINTER TO EventCode	-	≠ 0	Pointer to application variable which is type EventCode.

Initialization method return value

TRUE: All initialization parameters ok.

FALSE: Error in initialization parameter(s).

Operation

Input i_SupplyBeforeSafetySwitch (channel 1) and i_SupplyAfterSafetySwitch (channel 2) ADC values are converted to voltage values using hardware specific enumeration VALUE_AT_AD_MAXIMUM.U_SUPPLY as voltage value at AD maximum for both channels.

While i_SafetySwitch is FALSE and i_Enable is TRUE, channel 1 voltage is checked to be within allowed (given) limits and channel 2 voltage is checked to be less than hardware specific constant G_OUTPUT_SUPPLY_OFF_MAX_VOLT_AFTER_OVP. Voltage value of input i_SupplyAfterSafetySwitch is assigned to S_o_Voltage output.

While i_SafetySwitch is TRUE and i_Enable is TRUE, the input channel 1 and 2 voltages are monitored to be within allowed (given) limits and channel tolerance is monitored.

Tolerance monitoring checks that channel 2 voltage does not drop below channel 1 voltage by percentage defined in platform specific constant G_OUTPUT_SUPPLY_TOLERANCE.

The tolerance error is diagnosed after G_OUTPUT_SUPPLY_TOLERANCE_DIAG_DELAY.

If parameters and voltages are ok, o_SafetySwitch output follows the request of i_SafetySwitch input.

In case of parameter error, or if either of the voltages fail,

• The output o_SafetySwitch is set FALSE.

• Corresponding Error bit in o_Status structure is set TRUE

• Corresponding EventID is set to i_pEventCode

Inputs

Input variable name	Data type	Unit	Range	Description
i_Enable	BOOL	-	-	Enable POU operation
i_SafetySwitch	BOOL	-	-	Safety switch status request
i_SupplyBeforeSafetySwitch	DWORD	-	0 - G_ADC_MAXIMUM_VALUE	Measured channel 1 AD value
i_SupplyAfterSafetySwitch	DWORD	-	0 - G_ADC_MAXIMUM_VALUE	Measured channel 2 AD value

Outputs

Output variable name	Data type	Unit	Range	Description
o_SafetySwitch	BOOL	-	-	Safety switch output control status. This output is given as input for FW-provided function that controls diagnosed power group.
S_o_Voltage	SAFEDINT	mV	-	Validated output group control voltage.
o_Status	Status	-	-	Status of output value. See Status struct.

Error diagnostic

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

Conditions	S_o_Voltage	o_SafetySwitch	o_Status. OutputValid	o_Status error status	Event code FunctionID	Event code EventID
i_Enable TRUE AND init parameter error AND i_pEventCode valid	0	FALSE	FALSE	ParameterError	GROUP_CONTROL	PARAMETER_ERROR
i_Enable TRUE AND init parameter error AND i_pEventCode NULL	0	FALSE	FALSE	ParameterError	-	-
i_Enable TRUE AND init parameters ok AND ( i_SupplyBeforeSafetySwitch > G_ADC_MAXIMUM_VALUE OR i_SupplyAfterSafetySwitch > G_ADC_MAXIMUM_VALUE )	0	FALSE	FALSE	ParameterError	GROUP_CONTROL	PARAMETER_ERROR
i_Enable rises AND init parameters ok AND i_SafetySwitch TRUE AND voltages ok AND tolerance ok	Calculated voltage of channel 2	i_SafetySwitch	TRUE	-	NO_FUNC	NO_ERROR
i_Enable rises AND init parameters ok AND i_SafetySwitch FALSE AND channel 1 voltage ok AND channel 2 voltage < G_OUTPUT_SUPPLY_ OFF_MAX_VOLT_AFTER_OVP	Calculated voltage of channel 2	i_SafetySwitch	FALSE	-	NO_FUNC	NO_ERROR
i_Enable TRUE AND init parameters ok AND i_SafetySwitch TRUE AND voltages ok AND tolerance fault (channel 2 < channel 1 by more than G_OUTPUT_SUPPLY _TOLERANCE)	0	FALSE	FALSE	ValueMismatch	GROUP_CONTROL	DATA_MISMATCH
i_Enable TRUE AND init parameters ok AND channel 1 voltage < S_i_VoltageLowLimit)	0	FALSE	FALSE	OutputLow	GROUP_CONTROL	OUTPUT_TOO_LOW
i_Enable TRUE AND init parameters ok AND (channel 1 or 2 voltage > S_i_VoltageHighLimit)	0	FALSE	FALSE	OutputHigh	GROUP_CONTROL	OUTPUT_TOO_HIGH
i_Enable rises AND init parameters ok AND i_SafetySwitch FALSE AND channel 1 voltage ok AND channel 2 voltage >= G_OUTPUT_SUPPLY_OFF _MAX_VOLT_AFTER_OVP	0	FALSE	FALSE	ExternalVoltage	GROUP_CONTROL	EXTERNAL_VOLTAGE
i_Enable rises AND init parameters ok AND i_SafetySwitch TRUE AND channel 1 voltage ok AND channel 2 voltage < S_i_VoltageLowLimit	0	FALSE	FALSE	SafetySwitch Error	GROUP_CONTROL	VOLTAGE_SHORTCUT

Example code

Function block is included in hardware specific diagnostic program.

It is automatically generated to code template when MultiTool Creator is used.

Output group control and diagnostic is a safe-context POU.

Definitions:

VAR_INPUT

(* Output Group Control Inputs *)

i_Enable: BOOL := FALSE; // Enable operation

i_OutputGroup1Control: BOOL := FALSE; // Application status request for output group #1

i_SupplyBeforeSafetySwitch1:DWORD := DWORD#0; // Filtered ADC value for power supply before safety switch

i_SupplyAfterSafetySwitch1: DWORD := DWORD#0; // Filtered ADC value for power supply after safety switch

END_VAR

VAR_OUTPUT

(* Output Group Control Outputs *)

o_OutputGroup1ControlStatus: EPEC_SHWD.Status; // FB status

o_OutputGroup1Control_EC: EPEC_DITF.EventCode; // Event code

o_OutputGroup1Control: BOOL; // Group control status for controlling FB function

o_OutputGroup1ControlVoltage: SAFEDINT; // Measured output group control voltage

END_VAR

VAR

init_ok: BOOL; // Initialization status

outputGroupControl: EPEC_SHWD.S_OutputGroupControlAndDiagnostics; // POU instance

END_VAR

Init:

(* Output group control and diagnostic *)

init_ok := outputGroupControl.Init(

S_i_VoltageHighLimit := G_IO.OUTPUTGROUP1_HIGH_VOLTAGE_LIMIT, // Limit of overvoltage (mV)

S_i_VoltageLowLimit := G_IO.OUTPUTGROUP1_LOW_VOLTAGE_LIMIT, // Limit of undervoltage (mV)

S_i_DiagnosticDelay := G_IO.OUTPUTGROUP1_DIAGNOSTIC_DELAY, // Delay time (ms) for error diagnostic

i_pEventCode := ADR(o_OutputGroup1Control_EC) // Event code pointer for FB

);

Code:

(* Output group control and diagnostic *)

outputGroupControl(

i_Enable := i_Enable, // Enable operation

i_SafetySwitch := i_OutputGroup1Control, // Control request status

i_SupplyBeforeSafetySwitch := i_SupplyBeforeSafetySwitch1, // Filtered ADC value before safety switch

i_SupplyAfterSafetySwitch := i_SupplyAfterSafetySwitch1 // Filtered ADC value after safety switch

S_o_Voltage => o_OutputGroup1ControlVoltage, // Measured output group control voltage

o_SafetySwitch => o_OutputGroup1Control, // Output group control status for FW function

o_Status => o_OutputGroup1ControlStatus // FB status

);