Value limit describes the status of the value with regard to its defined limits. Limits Limit values are always defined within the configuration of particular object or structure item.
Limits might be are logically defined only for some selected object types and also for selected object value types.
D2000 system allows to define defines four limits: VHL, HL, LL and VLL. A The limit can be defined either directly - by entering a value , or its value can be determined defined by a system object (dynamic limit) - the button right from the input field.
| VHL | Very High Limit - the highest limit |
| HL | High Limit - high limit |
| LL | Low Limit - low limit |
| VLL | Very Low Limit - the lowest limit |
Values of individual limits determine the state of the object value according to its value. The relation object value - limits gives 6 possible states.
| Limit | Object status according to the relation Object value - Limit |
|---|---|
| Above VHL (object value > VHL) | |
| VHL | |
| Above HL (HL < object value ≤ VHL) | |
| HL | |
| Normal (LL ≤ object value ≤ HL) | |
| LL | |
| Below LL (VLL ≤ object value < LL) | |
| VLL | |
| Below VLL (object value < VLL) |
As Since the limits can be dynamic, i.e. determined by the object value (real or integer type), a situation , may occur when the relation VLL<LL<HL<VHL is not valid (limit crossing), may occur. The . Then, the object value is then in the status Limits Problem.
Hysteresis
Configuration This is configuration of the hysteresis relating to the limits defined for the object value. The hysteresis value (in %) is determined by the difference |VHL-VLL|. Hysteresis has effect on the evaluation of limit states of the object. Hysteresis is demonstrated on in the following figure.
The object value is in the status InLimit. This value breaks exceeds the limit HL (we assume , that the object value will not break exceed the level HL+HYSTERESIS - it is within the red-colored area in the figure). The value status is still InLimit. The system assigns the value state status HL to the object as soon as the value breaks exceeds the level HL+HYSTERESIS (the value is above the red-colored area in the figure). This is also valid also when the value is decreasing. The value gets the status InLimit as soon as it falls bellow the level HL-HYSTERESIS (the value is below the red-colored area in the figure).
