Outputs & PWM

Outputs are how your recipe controls the physical world. Each OUTPUT declared in VAR_OUTPUT maps to a PWM channel on the connected PowerUnit. Through PWM (Pulse Width Modulation), you control LED brightness, relay switching, and analog signal levels. Outputs also serve as the data link between the recipe and the XBB mobile app - the app displays each output’s current value, name, and status.

OUTPUT - PWM Output

The OUTPUT function block generates a PWM signal. It is also aliased as PWM100, PWM1000, INFO_ONOFF, INFO_VALUE, and INFO_GRAPH - the aliases control how the output is displayed in the app but the underlying behavior is identical.

Parameters

Basic Example

VAR_OUTPUT
    HELLJUS ["Helljus"] : OUTPUT;
    HALVLJUS ["Halvljus"] : OUTPUT;
END_VAR;

// Full brightness (100% duty cycle at 1kHz)
HELLJUS(VALUE := 1000, PERIOD := 1000);

// Half brightness (50% duty cycle at 1kHz)
HALVLJUS(VALUE := 500, PERIOD := 1000);

Calling OUTPUT Without PERIOD

If you call OUTPUT without specifying PERIOD, the firmware automatically converts any non-zero VALUE to 100% on. Specifically, the device normalizes the value to 1000 and sets PERIOD to 1000 internally.

VAR_OUTPUT
    EXTRALJUS ["Extraljus"] : OUTPUT;
END_VAR;

// These are all equivalent - 100% on:
EXTRALJUS(VALUE := 1);                        // No PERIOD: firmware converts to full on
EXTRALJUS(VALUE := 2);                        // No PERIOD: any non-zero = full on
EXTRALJUS(VALUE := TRUE);                     // No PERIOD: TRUE (=1) = full on
EXTRALJUS(VALUE := 1000, PERIOD := 1000);     // Explicit: 100% duty cycle

// This turns off the output:
EXTRALJUS(VALUE := 0);                        // Zero = off (with or without PERIOD)

PWM Timing Explained

The PERIOD parameter sets the PWM period in microseconds. The VALUE parameter sets the on-time within each period. The PWM frequency and duty cycle are calculated as:

Frequency (Hz)  = 1,000,000 / PERIOD
Duty cycle (%)  = VALUE / PERIOD * 100

Period and Frequency Examples

Common PWM Settings

Boolean Signals to OUTPUT

Boolean signals (BOOL) have the value 1 (TRUE) or 0 (FALSE). To drive an output fully on or fully off from a boolean, multiply by the period:

VAR
    SIGNAL_TANDNING : BOOL;
END_VAR;

VAR_OUTPUT
    IGNITION ["Tandning"] : OUTPUT;
END_VAR;

// Boolean * PERIOD: TRUE = full on (1000), FALSE = off (0)
IGNITION(VALUE := SIGNAL_TANDNING * 1000, PERIOD := 1000);

This technique works because TRUE * 1000 = 1000 (100% duty) and FALSE * 1000 = 0 (0% duty). It is more compact than an IF/ELSE block:

VAR
    SIGNAL_TANDNING : BOOL;
END_VAR;

VAR_OUTPUT
    IGNITION ["Tandning"] : OUTPUT;
END_VAR;

// Equivalent but more verbose - avoid this
IF SIGNAL_TANDNING THEN
    IGNITION(VALUE := 1000, PERIOD := 1000);
ELSE
    IGNITION(VALUE := 0, PERIOD := 1000);
END_IF;

Common Recipe Outputs

Most recipes include a set of standard system outputs that provide status information to the app and to other function blocks. Here is the typical set:

VAR_OUTPUT
    // System status outputs
    SYSTEM_ACTIVE ["System Active"] : OUTPUT;
    CAN_CONTROLLER ["CAN Controller"] : OUTPUT;
    VOLTAGE ["Voltage"] : INFO_VALUE;
    LOW_BATTERY ["Low Battery"] : INFO_ONOFF;
    ANALOG_IN0 ["Analog Input"] : INFO_VALUE;

    // Signal outputs (vehicle-specific)
    TANDNING ["Tandning"] : OUTPUT;
    HELLJUS ["Helljus"] : OUTPUT;
    HALVLJUS ["Halvljus"] : OUTPUT;
    BLINKERS_V ["Blinkers Vanster"] : OUTPUT;
    BLINKERS_H ["Blinkers Hoger"] : OUTPUT;
    BAKLJUS ["Bakljus"] : OUTPUT;
END_VAR;

VAR_SIGNAL
    HW : HARDWARE;
END_VAR;

VAR
    SIGNAL_TANDNING : BOOL;
    SIGNAL_HELLJUS : BOOL;
    SIGNAL_HALVLJUS : BOOL;
    SIGNAL_BLINKERS_V : BOOL;
    SIGNAL_BLINKERS_H : BOOL;
    SIGNAL_BAKLJUS : BOOL;
    canReady : BOOL;
END_VAR;

HW();

// System outputs
SYSTEM_ACTIVE(VALUE := 1000, PERIOD := 1000);                    // Always on
CAN_CONTROLLER(VALUE := canReady * 1000, PERIOD := 1000);        // CAN status
VOLTAGE(VALUE := TRUNC(HW.SUPPLY_VOLTAGE, INT), PERIOD := 1000); // Battery voltage
LOW_BATTERY(VALUE := (HW.SUPPLY_VOLTAGE < 11000) * 1000, PERIOD := 1000); // Warning < 11.0V
ANALOG_IN0(VALUE := TRUNC(HW.ANALOG_IN0, INT), PERIOD := 1000);  // Analog input

// Vehicle signal outputs
TANDNING(VALUE := SIGNAL_TANDNING * 1000, PERIOD := 1000);
HELLJUS(VALUE := SIGNAL_HELLJUS * 1000, PERIOD := 1000);
HALVLJUS(VALUE := SIGNAL_HALVLJUS * 1000, PERIOD := 1000);
BLINKERS_V(VALUE := SIGNAL_BLINKERS_V * 1000, PERIOD := 1000);
BLINKERS_H(VALUE := SIGNAL_BLINKERS_H * 1000, PERIOD := 1000);
BAKLJUS(VALUE := SIGNAL_BAKLJUS * 1000, PERIOD := 1000);

App Display Limitations

VAR
    currentBrightness : INT;
END_VAR;

VAR_OUTPUT
    // This will show correctly (0-255 range)
    BRIGHTNESS ["Ljusstyrka"] : INFO_VALUE;

    // This drives a physical output (PWM) - app shows 0-255
    LED_OUT ["LED"] : OUTPUT;
END_VAR;

// INFO_VALUE for display: shows the actual number
BRIGHTNESS(VALUE := currentBrightness, PERIOD := 255);

// OUTPUT for PWM: controls hardware, app shows 0-255
LED_OUT(VALUE := currentBrightness * 4, PERIOD := 1000);

Checking if an Output is Connected

The USED output tells you whether this output channel is physically connected to a PowerUnit. This is useful for conditional logic - you can skip expensive CAN requests for signals that have no physical output connected:

VAR_SIGNAL
    HW : HARDWARE;
END_VAR;

VAR_OUTPUT
    HELLJUS ["Helljus"] : OUTPUT;
END_VAR;

VAR
    ENABLE_HELLJUS : BOOL := FALSE;
END_VAR;

HW();

IF HELLJUS.USED OR HW.HOST_CONNECTED THEN
    // Only read the high beam DID if:
    // - The output is physically connected to a PowerUnit channel, OR
    // - The app is connected (user wants to see the value)
    ENABLE_HELLJUS := TRUE;
END_IF;

HELLJUS(VALUE := ENABLE_HELLJUS * 1000, PERIOD := 1000);

Output Types Summary

All output types use the same underlying OUTPUT function block. The type name controls how the output appears in the XBB mobile app:

Type Selection Examples

VAR_SIGNAL
    HW : HARDWARE;
END_VAR;

VAR
    brightness : INT;
    SIGNAL_TANDNING : BOOL;
    rpmValue : INT;
END_VAR;

VAR_OUTPUT
    // Physical PWM output for LED strip
    LED_STRIP ["LED Strip"] : OUTPUT;

    // Show ignition status as on/off toggle
    IGN_STATUS ["Tandning"] : INFO_ONOFF;

    // Show battery voltage as a number
    BATT_VOLTAGE ["Batteri (V)"] : INFO_VALUE;

    // Show RPM as a live graph
    ENGINE_RPM ["Varvtal"] : INFO_GRAPH;
END_VAR;

HW();

// Physical output: PWM dimming
LED_STRIP(VALUE := brightness, PERIOD := 1000);

// Info on/off: boolean * period
IGN_STATUS(VALUE := SIGNAL_TANDNING * 1000, PERIOD := 1000);

// Info value: direct value
BATT_VOLTAGE(VALUE := TRUNC(HW.SUPPLY_VOLTAGE, INT), PERIOD := 1000);

// Info graph: direct value (app draws the graph over time)
ENGINE_RPM(VALUE := rpmValue, PERIOD := 10000);

Dimming and Fade Patterns

Variable Brightness from CAN Signal

Map a CAN byte value (0–255) to PWM duty cycle:

VAR
    dimLevel : BYTE;   // From CAN data (0-255)
END_VAR;

VAR_OUTPUT
    INTERIOR_LIGHT ["Innerbelysning"] : OUTPUT;
END_VAR;

// Scale 0-255 to 0-1000 for PWM
INTERIOR_LIGHT(VALUE := dimLevel * 4, PERIOD := 1000);

Two-Level Output (Position + Full)

A common pattern for vehicle lights: dim for position/parking, full for active:

VAR
    SIGNAL_BAKLJUS : BOOL;       // Tail light signal
    SIGNAL_BROMS : BOOL;         // Brake signal
    outputValue : INT;
END_VAR;

VAR_OUTPUT
    TAIL_LIGHT ["Bakljus"] : OUTPUT;
END_VAR;

// Brake = 100%, tail light = 20%, off = 0%
IF SIGNAL_BROMS THEN
    outputValue := 1000;         // Full brightness
ELSIF SIGNAL_BAKLJUS THEN
    outputValue := 200;          // 20% for position light
ELSE
    outputValue := 0;
END_IF;

TAIL_LIGHT(VALUE := outputValue, PERIOD := 1000);