Moist Function Block Implementation

The Code is implemented in accordens to the requirments given in the function description. Quickly summerized it describes the following,

• Survey and report the moisture in the air,
• Sound  an alarm after 10 mintues if the moisture deviates more than +-5%rH away from the setpoint.
• In case of an alarm, turn on fans to ensure a well ventilated facility

The Code for the Moisture sensor is based on its technical data, where 0v = 0%rH[NOT VERIFIED]  which linearly scales to 10v = 100%rH[NOT VERIFIED]. This means that linear interpolation is utilized to scale the input voltage too an output in %rH.

Linear interpolation is performed with the following function,

This means that the inputs needs to be,

• sensor_reading:REAL;
• set_point_in_pRhREAL;
• alarm_delay:TIME;
• max_pRh:REAL;
• max_pRh_in_volts:REAL;
• min_pRh:REAL;
• min_pRh_in_volts:REAL;

And the outputs needs to be,

• pRh_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 new function block looks as following,