The following example shows how the Linear programming block can be used to scale values.
The Linear programming block can be used to scale a hot water supply setpoint. When the Outside Air Temperature (OAT) is 41°F, the hot water supply setpoint is 203°F; and when the OAT is 59°F, the hot water supply setpoint is 158°F. OATs between 41°F and 59°F result in a hot water supply setpoints that are scaled between 203°F and 158°F.
Consider an OAT of 52°F.
If ( x1, y1) = (41, 203)
and, (x2, y2) = (59, 158)
and, if the In slot has a value of 52°F then hot water setpoint in °F :
If the two points given above and the OAT of 52°F are on the inputs to the Linear programming block, the Linear programming block will output a value of 175.5°F.
| Note: | The Linear programming block does not constrain the output value. If limits are required, use the Limit programming block, described on page , to constrain the output values. |
Inputs |
|
|||||
|
Slots |
Type |
Default |
Description |
||
|
In |
Numeric |
Null |
The input value. |
||
|
X1 |
Numeric |
0.0 |
Value for x1 |
||
|
X2 |
Numeric |
100.0 |
Value for x2 |
||
|
Y1 |
Numeric |
0.0 |
Value for y1 |
||
|
Y2 |
Numeric |
100.0 |
Value for y2 |
||
Outputs |
|||
|
Slots |
Type |
Description |
|
Out |
Numeric |
The output value calculated using the above formula. If any of the inputs are Null, the output is also Null. |