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Digital I/O Components

All digital I/O components extend Component and implement I_DigitalInput or I_DigitalOutput. They support hardware forcing via E_ForceState.

DigitalInput_NO (Normally Open)

Wraps a hardware BOOL input. IsActive reflects the raw input unless forced.

Interface

Member Type Description
FB_Init(Name, Input) Constructor Input is a REFERENCE TO BOOL pointing to the hardware variable
IsActive BOOL (Get) TRUE when the physical input is TRUE (or forced on)
Force E_ForceState (Get/Set) Unforced / ForceOn / ForceOff

Example

// From DigitalInput_NO_TEST
VAR
    Input        : BOOL;
    Di           : DigitalInput_NO('PartPresent', Input);
END_VAR

// Normal operation
Di.Force := E_ForceState.Unforced;
Input    := TRUE;
// Di.IsActive -> TRUE

Input := FALSE;
// Di.IsActive -> FALSE

// Force on regardless of hardware
Di.Force := E_ForceState.ForceOn;
Input    := FALSE;
// Di.IsActive -> TRUE

// Force off regardless of hardware
Di.Force := E_ForceState.ForceOff;
Input    := TRUE;
// Di.IsActive -> FALSE

DigitalInput_NC (Normally Closed)

Same as DigitalInput_NO but with inverted logic — IsActive is TRUE when the hardware input is FALSE.

Interface

Identical to DigitalInput_NO.

Member Description
IsActive TRUE when physical input is FALSE (i.e., circuit is closed / contact not broken)

Example

VAR
    Input : BOOL;
    Di    : DigitalInput_NC('EStop', Input);
END_VAR

Input := FALSE;   // circuit closed — no E-Stop
// Di.IsActive -> TRUE

Input := TRUE;    // circuit open — E-Stop triggered
// Di.IsActive -> FALSE

DigitalOutput

Wraps a hardware BOOL output. Writing to On drives the hardware variable.

Interface

Member Type Description
FB_Init(Name, Output) Constructor Output is a REFERENCE TO BOOL pointing to the hardware variable
On BOOL (Get/Set) Command the output; drives the hardware variable
Force E_ForceState (Get/Set) Unforced / ForceOn / ForceOff

Example

VAR
    DoSeal  : BOOL;
    Seal    : DigitalOutput('SealSolenoid', DoSeal);
END_VAR

Seal.On := TRUE;   // DoSeal -> TRUE (hardware coil energised)
Seal.On := FALSE;  // DoSeal -> FALSE

// Force on regardless of command
Seal.Force := E_ForceState.ForceOn;
Seal.On    := FALSE;
// DoSeal -> TRUE (forced)

DigitalInput_Combiner

Combines two I_DigitalInput references with AND or OR logic into a single IsActive signal.

Interface

Member Type Description
FB_Init(Name, InputA, InputB, Mode) Constructor Mode: E_CombinerMode.And or E_CombinerMode.Or
IsActive BOOL (Get) Result of the logical combination

Example

VAR
    DiA, DiB   : BOOL;
    InputA     : DigitalInput_NO('SensorA', DiA);
    InputB     : DigitalInput_NO('SensorB', DiB);
    Combiner   : DigitalInput_Combiner('BothPresent', InputA, InputB, E_CombinerMode.And);
END_VAR

DiA := TRUE; DiB := TRUE;
// Combiner.IsActive -> TRUE

DiA := TRUE; DiB := FALSE;
// Combiner.IsActive -> FALSE

DigitalInput_DebounceRisingEdge / DigitalInput_DebounceFallingEdge

Wraps a digital input and only passes the state change after it has been stable for a configurable debounce time.

Interface

Member Type Description
FB_Init(Name, Input, DebounceTime) Constructor DebounceTime: TIME value for stability window
IsActive BOOL (Get) Debounced output
CyclicLogic() Method Must be called each scan