Heidenhain-Threshold

Threshold trigger executes a data transfer with off-limit condition (of Heidenhain value)

The properties are:

Access data	Select a set of Heidenhain access data.
Item	Item whose off-limit condition will execute the transfer. Browse items with tag browser (“...” button).
Threshold	Absolute value.
Trigger if item	Set if threshold has to be under- or overrun.
Hysteresis	If the trigger has executed the transfer once, it might be required that the trigger is re-released only if the Heidenhain item’s value is clearly different from threshold value. If this is the case, please specify the difference between Heidenhain item and threshold with which the trigger is set active again. Example: The threshold is 20 °C, to be triggered when overrun. Temperature varies between 19 and 21 degrees, but only the first overrun has to be transferred. Hysteresis could be set to 18 degrees absolute value. Thus, the trigger will only release after the temperature has fallen below 18 (after having overrun 20).

tip

Tip: If the connection should be triggered permanently on off-limit condition, set hysteresis absolute value to the maximum value the item can take. Thus, it will trigger in OPC Routers cycle time interval as long as it is in off-limit condition. Combine with a data change trigger linked with AND to only trigger data changes above the limit. In the example above, the temperature will not exceed 100 degrees, then with threshold = 20 and trigger reset from 100 absolute value the trigger would always trigger when the temperature is between 20 and 100 degrees, in the frequency of the cycle time of the router (settings). You could limit this with an AND-linked datachange trigger to record only the data changes above the threshold.