Tolerance band monitoring
General
The settings for the behaviour of the tolerance band violation are made in smartWARE Setup in the area Configuration under 
> PLC configuration > Prog. generator > Program generator x > Tolerance range monitoring.
A tolerance band can be placed around the first setpoint (setpoint 1). Whilst the program is running, the Actual value must be within the tolerance band. Otherwise, there is a tolerance band violation. If the tolerance band is violated, the program in question is stopped until the Actual value is back within the band.
Parameter | Selection/settings | Description |
|---|---|---|
Alarm type | Inactive Event Alarm | Function is inactive. Alarm leads to an entry in the event list. Alarm leads to an entry in the alarm list. |
Alarm at level | High (1) Low (0) | Alarm at high level (1) Alarm at low level (0) |
Event text | Use the default names or edit the text. | Text that is entered into the event list when an alarm occurs. |
Stop on exceeded tolerance band | Yes No | Program generator is stopped on alarm. Program generator is not stopped on alarm. |
The actual value for tolerance band monitoring is transferred to the program generator in the PLC project. For this, the following retrievel is required:
// Actual value from sensor is assigned to program controller 1 for tolerance range monitoring.stOem.astProgramGenerator[1].stIN.stToleranceBand.rActualValue := rTemperatureSensor;
Hysteresis for tolerance band monitoring
General
The hysteresis in tolerance band monitoring is a switching differential that prevents the actual value at the limit value from constantly resetting the alarm.
The working principle of the hysteresis is described in the following example. The hysteresis is symmetrical around the tolerance band limits. If the actual value exceeds the upper tolerance band limit + hysteresis (> 26 in the example), an alarm is triggered. The alarm is only reset when the upper tolerance band limit - hysteresis is (in the example < 24) is not achieved.
The lower tolerance band limit behaves in the same way.
How is the hysteresis set?
The hysteresis for tolerance band monitoring is transferred to the program generator in the PLC project. For this, the following retrievel is required:
// Hysteresis is assigned to program controller 1 for tolerance range monitoring.stOem.astProgramGenerator[1].stIN.stToleranceBand.rHysteresis := 1.0;
