HBridgeControllerDO

Supported platforms: CODESYS 3.5 SP19 SAFETY

S_HBridgeControllerDO (FB)

Description

S_HBridgeControllerDO POU implements logic to control and diagnose H-Bridge with DO signals. It can be used to control for example electric motor or linear actuator.

POU can be used with DO pins which gives possibility to control both pin high and low side.

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

Do not call Init method when control is active.

Initialization parameters

Parameter	Type	Unit	Range	Description
S_i_OverCurrentLimit	SAFEUINT	mA	-	Limit for overcurrent diagnostic.
S_i_CurrentDiagnosticDelay	SAFEUINT	ms	-	Diagnostic delay for current diagnostic
S_i_ControlStopDelay	SAFEUINT	ms	-	Delay time for waiting motor/actuator stop.
i_pEventCode	POINTER TO EventCode	-	≠ 0	Pointer to application variable where event code is stored.

Initialization method return value

TRUE: All initialization parameters ok.

FALSE: Error in initialization parameter(s).

Operation

POU is in normal operation mode if

• The control is enabled, i.e. i_Enable is TRUE AND no error diagnosed.

In normal operation DO outputs are controlled according to control request signals S_i_Forward and S_i_Backward, see table below.

S_i_Forward	S_i_Backward	Motor/Actuator Control Direction	Pin1 HS DO	Pin2 HS DO	Pin1 LS DO	Pin2 LS DO
FALSE	FALSE	-	FALSE	FALSE	FALSE	FALSE
TRUE	FALSE	Forward	TRUE	FALSE	FALSE	TRUE
FALSE	TRUE	Backward	FALSE	TRUE	TRUE	FALSE
TRUE	TRUE	-	FALSE	FALSE	FALSE	FALSE

POU's internal state machinePOU's internal state machine

Internally POU has state machine of type HBridgeStates.

State	Description
Idle	S_i_Forward = FALSE andS_i_Backward = FALSE. DO outputs are set FALSE.
StartControl	Depending on the control direction, either Pin1 or Pin2 HS DO is first set TRUE. Wait that both pin's DOS statutes rise. LS DO of pin pair* is set TRUE
Control	Control continues until control request is reset, control direction changes or any error occurs.
EndControl	HS DO is set first to FALSE Wait i_ControlStopDelay time LS DO of pin pair* is set FALSE Diagnostic is disabled in this state, because running motor may induce electricity to outputs and cause unnecessary alarms.
Error	Error is diagnosed. DO outputs are set FALSE.
ControlDisabled	Control is disabled. see Control_disabled_reasons

* Pin pair: If pin 1 HS DO is controlled, the pin pair is pin 2. If pin 2 HS DO is controlled, the pin pair is pin 1.

Error Diagnostics

Conditions	DO outputs	o_Status. OutputValid	o_Status error status	Event code FunctionID	Event code EventID
i_Enable = TRUE AND i_pEventCode = NULL	FALSE	FALSE	ParameterError	-	-
i_Enable rises AND (S_i_Forward OR S_i_Backward is TRUE)	FALSE	FALSE	StartupError	H_BRIDGE	STARTUP_ERROR
i_Enable = TRUE AND (i_Pin1OverCurrentProtectionStatus OR i_Pin2OverCurrentProtectionStatus is TRUE)	FALSE	FALSE	Pin1OverCurrent/ Pin2OverCurrent	H_BRIDGE	OVER_CURRENT
i_Enable = TRUE AND (i_Pin1Current OR i_Pin2Current < 0)	FALSE	FALSE	InputLow	H_BRIDGE	INPUT_TOO_LOW
i_Enable = TRUE AND S_i_Forward = TRUE AND S_i_Backward = TRUE	FALSE	FALSE	ParameterError	H_BRIDGE	PARAMETER_ERROR
i_Enable = TRUE AND (i_Pin1DOStatus OR i_Pin2DOStatus is FALSE when the corresponding output is controlled)	FALSE	FALSE	Pin1ShortToGround/ Pin2ShortToGround¹	H_BRIDGE¹	VOLTAGE_SHORTCUT¹
i_Enable = TRUE AND (i_Pin1DOStatus OR i_Pin2DOStatus is TRUE when the corresponding output is not controlled)	FALSE	FALSE	Pin1ExternalVoltage/ Pin2ExternalVoltage¹	H_BRIDGE¹	EXTERNAL_VOLTAGE¹
i_Enable = TRUE AND (i_Pin1Current OR i_Pin2Current > G_HBRIDGE_CURRENT_LIMIT_CONTROL_OFF (HW specific constant) when the corresponding output is not controlled)	FALSE	FALSE	Pin1CurrentLeak/ Pin2CurrentLeak²	H_BRIDGE²	OVER_CURRENT²
i_Enable = TRUE AND (i_Pin1Current OR i_Pin2Current > S_i_OverCurrentLimit)	FALSE	FALSE	Pin1OverCurrent/ Pin2OverCurrent²	H_BRIDGE²	OVER_CURRENT²

¹⁾ After voltage diagnostic delay (60 ms) is elapsed. Note! Diagnostic is disabled when o_BridgeState = EndControl.

²⁾ After diagnostic delay S_i_CurrentDiagnosticDelay is elapsed. Note! Diagnostic is disabled when o_BridgeState = EndControl.

The o_Status error bits and EventCode error are not reset before the rising edge of i_Enable input.

Inputs

Input variable name	Data type	Range	Description
i_Enable	BOOL		Enable POU operation
S_i_Forward	BOOL		Run motor forward
S_i_Backward	BOOL		Run motor backward
i_Pin1DOStatus	BOOL		Pin 1 output digital status (DOS)
i_Pin2DOStatus	BOOL		Pin 2 output digital status (DOS)
i_Pin1Current	BOOL		Measured pin 1 current (mA)
i_Pin2Current	BOOL		Measured pin 2 current (mA)
i_Pin1OverCurrentProtectionStatus	BOOL		Pin 1 overcurrent status from FW
i_Pin2OverCurrentProtectionStatus	BOOL		Pin 2 overcurrent status from FW

Outputs

Output variable name	Data type	Range	Description
o_Pin1HsDO	BOOL		Pin 1 high side DO control
o_Pin2HsDO	BOOL		Pin 2 high side DO control
o_Pin1LsDO	BOOL		Pin 1 low side DO control
o_Pin2LsDO	BOOL		Pin 2 low side DO control
o_Status	Status		Status of control outputs
o_BridgeState	HBridgeStates		Bridge control sequence state
o_Forward	BOOL		Motor/Actuator forward control active
o_Backward	BOOL		Motor/Actuator backward control active

o_BridgeState value ControlDisabled is not necessary error situation. It can mean one of the following:

Motor/actuator is not connected or wiring is broken
- Check wiring
Actuator has been driven to its end position
- Deactivate control request and try to control other direction
pin LS FET is shortcut to ground
- Deactivate control request and try to control other direction

o_BridgeState value Error indicates error state. Check o_Status output to identify error.

Control can be retried after resetting POU i.e. set input i_Enable to false and then true.

Example code

Definitions:

hBridgeControl: EPEC_SHB.S_HBridgeControllerDO;
inited: BOOL;

// POU input variables
eventCode :    EPEC_DITF.EventCode;
enable: BOOL;
controlForward: BOOL; // Control request for example from control unit DI
controlBackward:BOOL;  // Control request for example from control unit DI
pin1DOStatus : BOOL; // DO pin 1 DOS
pin2DOStatus: BOOL;  // DO pin 2 DOS

pin1Current: DINT; // DO pin 1 measured current
pin2Current: DINT; // DO pin 2 measured current

// POU output variables
pin1HsDO: BOOL; // Control to DO pin 1 high side
pin2HsDO: BOOL;  // Control to DO pin 2 high side
pin1LsDO: BOOL;  // Control to DO pin 1 low side
pin2LsDO: BOOL;  // Control to DO pin 2 low side
status: EPEC_SHB.Status;
bridgeState:   EPEC_SHB.HBridgeStates;

Safety Code:

IF NOT inited THEN

// Call POU init method to initialize parameters.
hBridgeControl.Init(

S_i_OverCurrentLimit := UINT#6000,

S_i_CurrentDiagnosticDelay := UINT#500,

S_i_ControlStopDelay := UINT#500,

i_pEventCode:= ADR(eventCode));
inited := TRUE;
END_IF

hBridgeControl(
   i_Enable:= enable,
   S_i_Forward:= controlForward,
   S_i_Backward := controlBackward,
   i_Pin1DOStatus:= pin1DOStatus,
   i_Pin2DOStatus:= pin2DOStatus,
   i_Pin1Current:= pin1Current,
   i_Pin2Current:= pin2Current,
   o_Pin1HsDO=> pin1HsDO,
   o_Pin2HsDO=> pin2HsDO,
   o_Pin1LsDO=> pin1LsDO,
   o_Pin2LsDO=> pin2LsDO,
   o_Status=> status,
   o_BridgeState=> bridgeState,
   o_Forward=> ,
   o_Backward=> );

IF bridgeState = EPEC_SHB.HBridgeStates.ControlDisabled THEN
// Control disabled. Inform user to try control other direction.
;

ELSIF bridgeState = EPEC_SHB.HBridgeStates.Error THEN
// Error handling. Error can be identified from status variable.
;
END_IF

Assignments to actual I/O variables is not implemented in this example.