PROGRAM AlarmSample
        VAR
            i2c_fd : DINT := -1;
            count : DINT := 0;
            inputs : ARRAY[0..7] OF BOOL;
            outputs : ARRAY[0..7] OF BOOL;
            alarm_activated : BOOL := TRUE;
            activation_trigger : R_TRIG;
        END_VAR

        IF i2c_fd < 1 THEN
           i2c_fd := I2C_open(bus_id := 1);
        ELSIF i2c_fd >= 0 THEN
            inputs := I2C_PCF8574_read(fd := i2c_fd, address := 16#38);

            activation_trigger(CLK := inputs[7]);
            IF activation_trigger.Q THEN
                alarm_activated := NOT alarm_activated;
                outputs[0] := FALSE;
            END_IF;

            IF alarm_activated THEN
                FOR count := 0 TO 6 BY 1 DO
                    IF NOT inputs[count] THEN
                        outputs[0] := TRUE;
                        EXIT;
                    END_IF;
                END_FOR;
            END_IF;

            I2C_PCF8574_write(fd := i2c_fd, address := 16#20, pin_values := outputs);
        END_IF;
END_PROGRAM