SingleCurrentValveController (FB)

Epec Programming and Libraries Manual

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Supported platforms: CODESYS 3.5

SingleCurrentValveController (FB)

Description

This FB handles single current controlled proportional valve in products that do not have built-in controller.

The FB includes end attenuation, ramp and control curve progression.

A startup error is diagnosed if control is requested on the rising edge of i_Enable.

The output control signal is set to zero if i_Enable is FALSE, parameter error is diagnosed or startup error is diagnosed.

All internal FB initializations are done on the rising edge of i_Enable.

All errors are reset on the rising edge of i_Enable.

Limitations

The FB uses internally SafeProportionalValveControl librarys FBs:

S_EndAttenuation

S_LinearRamp

S_CurrentRequest

S_AdaptiveController

Following parameters are taken into use at the rising edge of i_Enable:

- i_MaximumCurrent

- i_MinimumCurrent

- i_CoilResistance

- i_OverCurrentLimit

- i_WireBrokenLimit

- i_CorrectionParameter

- i_ImpulseUpParameter

- i_PI_P

- i_PI_I

- i_AttenuationLimit

- i_AscendRampTime

- i_DescendRampTime

- i_DiagnosticDelay

+ Any initialized event code.

Inputs

Input variable name	Data type	Range	Description
i_Enable	BOOL	FALSE/TRUE	Enables controlling of the PWM outputs
i_Control	INT	0..10000	Control signal from e.g. joystick.
i_MeasuredCurrent	UDINT	0..i_OverCurrentLimit	Measured current (mA).
i_SupplyVoltage	DINT	-	Measured supply voltage (mV).
i_AttenuationOn	BOOL	FALSE/TRUE	End attenuation sensor activity status.
i_MaximumCurrent	UINT	0..5000	Maximum current of valve (mA)
i_MinimumCurrent	UINT	0..5000	Minimum current of valve (mA)
i_CoilResistance	UDINT	> 0	Coil resistance (mΩ).
i_OverCurrentLimit	UINT	> S_i_Wire BrokenLimit and <= 5000	Over current error limit (mA).
i_WireBrokenLimit	UINT	0..5000	Wire broken error limit (mA).
i_CorrectionParameter	UINT	-	Correction factor parameter. 1000 is a neutral value.
i_ImpulseUpParameter	UINT	-	Impulse up factor parameter. Bigger value means higher impulse. 0 = use default impulse (1000). Impulse can be disabled with AdvancedInit method.
i_PI_P	UDINT	>0*	PI controller p-value
i_PI_I	UDINT	>0*	PI controller i-value with two decimals, 1 = 0,01.
i_AttenuationLimit	UINT	0..100%	End attenuation limit. Percentage from maximum control value 10000.
i_AscendRampTime	UINT	-	Time (ms) of o_PWMRatio signal to change from center to positive max (0->10000).
i_DescendRampTime	UINT	-	Time (ms) of o_PWMRatio signal to change from positive max to center (10000->0).
i_DiagnosticDelay	UINT	-	Diagnostic delay (ms) for overcurrent/wire broken errors.

*Normally, value >0. PI-controller can be disabled by setting i_PI_P=0 and i_PI_I=0. This is required when finding the optimal i_CorrectionParameter value. See: S_AdaptiveController (FB), section Adjusting correction parameters.

Outputs

Output variable name	Data type	Range	Description
o_PWMRatio	DWORD	HW specific	Output value to PWM pin. Maximum value EPEC_HW.Constants.G_PWM_OUT_MAX_VALUE
o_InputHigh	BOOL	FALSE/TRUE	i_Control too high.
o_InputLow	BOOL	FALSE/TRUE	i_Control too low.
o_StartupError	BOOL	FALSE/TRUE	Control request on already when i_Enable rises.
o_OverCurrentError	BOOL	FALSE/TRUE	Overcurrent error is detected.
o_WireBrokenError	BOOL	FALSE/TRUE	Wire broken error is detected.
o_PI_I_TermError	BOOL	FALSE/TRUE	PI-controller I-term has reached it's limits.
o_ParameterError	BOOL	FALSE/TRUE	Incorrect parameter value in any of the monitored parameters.

AdvancedInit (Public Method)

This optional method set controlling parameters for controller.

Inputs

Input variable name	Data type	Range	Description
i_Enable	BOOL	FALSE/TRUE	Enable operation.
i_CurrentChangeSpeed	UINT	>0	Current change speed mA/ms.
i_UseImpulse	BOOL	FALSE/TRUE	Impulse is used when current request changes more than i_ParStep.
i_LearnOn	BOOL	FALSE/TRUE	Adaptive controller learning, yet to be implemented.
i_StartImpulseTime	UINT	-	How long start impulse is active. Parameter affects only if i_AutomaticStartImpulse is false
i_AutomaticStartImpulse	BOOL	FALSE/TRUE	Controller automatically set start impulse when current request is deviated from 0.

CorrectionParameterInit (Public Method)

This optional method can be used for setting an array of correction and impulse parameters for controllers.

Inputs

Input variable name	Data type	Range	Description
i_Enable	BOOL	FALSE/TRUE	Enable operation.
i_pCorrectionParameters	POINTER TO UINT	>0	Pointer to first correction factor parameter.
i_pImpulseUpParameters	POINTER TO UINT	>0	Pointer to first impulse up factor parameter.
i_pImpulseDownParameters	POINTER TO UINT	>0	Pointer to first impulse down factor parameter.
i_ParameterCount	UINT	-	Parameter count.
i_ParStep	UINT	>0	Difference (mA) between consecutive correction factor parameters.

EventCodeInit (Public Method)

This optional method sets pointer for event code.

Inputs

Input variable name	Data type	Description
i_Enable	BOOL	Enable operation.
i_pEventCode	POINTER TO EPEC_DITF.EventCode	Pointer to signal event code value provided by the application.

Error diagnostic

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

FunctionID and EventID are only set if EventCode is used.

A parameter error is diagnosed if:

i_AttenuationLimit out of range OR
i_MinimumCurrent >= i_MaximumCurrent OR
i_OverCurrentLimit out of range OR
i_WireBrokenLimit >= i_OverCurrentLimit OR

Conditions	o_PWMRatio	Output error set TRUE	Event code FunctionID	Event code EventID
i_Enable TRUE AND parameter error AND i_pEventCode valid	0	o_ParameterError	depends on the parameter	PARAMETER_ERROR
i_Enable TRUE AND parameter error AND i_pEventCode NULL	0	o_ParameterError	-	-
i_Enable rises AND parameters ok AND i_Control <> 0	0	o_StartupError	CURRENT CONTROLLER	STARTUP_ERROR
i_Enable TRUE AND init parameters ok AND S_i_Control within range	PWM ratio	-	NO_FUNC	NO_ERROR
i_Enable TRUE AND init parameters ok AND S_i_Control > 10000	0	o_InputHigh	END_ATTENUATION	INPUT_TOO_HIGH
i_Enable TRUE AND parameters ok AND S_i_Control < -10000	0	o_InputLow	END_ATTENUATION	INPUT_TOO_LOW
i_Enable TRUE AND parameters ok AND i_CurrentMeasured > i_OverCurrentLimit	0	o_OverCurrentError	CURRENT CONTROLLER	OVER_CURRENT
i_Enable TRUE AND parameters ok AND i_CurrentRequest > 0 AND i_CurrentMeasured < i_WireBrokenLimit	0	o_WireBrokenError	CURRENT CONTROLLER	WIRE_BROKEN
i_Enable TRUE AND parameters ok AND PI controller internal integrator (I) term out of limits	PWM ratio	o_PI_I_TermError	NO_FUNC	NO_ERROR

Example code

How to use SingleCurrentValveController as traditional PI-controller

It is possible to use SingleCurrentValveController as traditional PI-controller by using the following settings:

Call AdvancedInit method once with the following input values
- i_Enable = TRUE
- i_UseImpulse = FALSE.
- i_CurrentChangeSpeed = 5000 mA/ms. This ensures that PI-controller is activated immediately.
- Other inputs can be FALSE/0.
Set main block input i_CorrectionParameter to value 1. Other inputs can be application specific.