Issue
How to use secondary values in programmable points.
How to use forecast in programmable points.
Environment
BAS
SIGMA
Cause
Some objects in Sigma and BAS have secondary values:
- Time Schedule - minutes to next switch (when the time schedule is going to change state) is displayed. An example of this is to bring on the heating plant 30 minutes before an AHU starts.
- Optimiser - minutes to next switch (when the optimiser is going to change state) is displayed. An example of this is to bring on the boiler plant 30 minutes before an VT cct starts.
- Rotation - the lead load no. is displayed. An example of this is to determine the lead load when a modulating burner signal is used.
- DO and DI - the hours run is displayed. An example of this is to do pump changeover on hours run.
Resolution
Example:
For a Time schedule:
10 xflo = P100 (timeschedule object) forecast
20 if P100 off and xflo < 30.0 then return true "Plant PreHeat"
30 if P100 on then return true "Time On"
40 return false "Time Off"
For a Rotation object with 2 loads:
10 xflo = P120 (rotation object) forecast
20 if aflo=1.0 then return true "Boiler1 Lead"
30 if aflo=2.0 then return true "Boiler2 Lead"
40 return false "false"
Note: aflo is used as a global variable to another object in the same controller, if not required then substitute with xflo.
