Industrielle styresystemer - Wiki
he Code is implemented in accordens to the requirments given in the function description. Quickly summerized it describes the following,
- Survey and report the CO2 levels in the rom
- Sound an alarm after 10 mintues if the temperature deviates more than +-200ppm away from the setpoint
- In case of an alarm, turn on fans to ensure a well ventilated facility
The Code for the Temperature sensor is based on its technical data, where 0v = 0ppm[NOT VERIFIED] which linearly scales to 10v = 4000ppm[NOT VERIFIED]. This means that linear interpolation is utilized to scale the input voltage too an output in ppm.
Linear interpolation is performed with the following function,
This means that the inputs needs to be,
- sensor_reading:REAL;
- set_point_in_ppm:REAL;
- alarm_delay:TIME;
- max_ppm:REAL;
- max_ppm_in_volts:REAL;
- min_ppm:REAL;
- min_ppm_in_volts:REAL;
And the outputs needs to be,
- ppm_read:REAL;
- alarm_high:BOOL;
- alarm_low:BOOL;
With the following internal variables,
- alarm_since_trig:TIME;
- alarm_high_trig:BOOL;
- alarm_low_trig:BOOL;
- alarm_high_trig_0:BOOL;
- alarm_low_trig_0:BOOL;
The coded implementation looks like this,
Visually the function block looks as following,
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