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L-VIS User Manual
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Set the Alarm Condition to Above Max. and enter a time delay of for example 3s. This will
require the user to press and hold the button for 3 seconds, before the alarm will be cleared.
Enter a value between 0 and 1 for the maximum of the data point value range, for example
0.5 would be a good value. For the Action, select Set on Alarm Enter and select the desired
output value for a cleared alarm from the dropdown list named Value for Alarm Set Action.
This is because we actually define an alarm condition when the button is pressed. As a
result of this alarm condition, we then reset the ‘real’ alarm.
NOTE:
The above examples may of course be combined, to have automatic alarm clear when the
temperature falls below T2 and manual clear via a button when the temperature is at least
below T1.
8.12 Data Point Connectors
Data Point Connector objects are used to receive a value from one or more input data points
and copy the received value to all connected output data points or other objects which
accept a value, for example action objects.
A data point connector has no visible representation on the display and is therefore not
related to any of the visible objects. It can only be connected to a collection object, as
described earlier. To create a new data point connector, use the context menu of the
collection object to which you want to add the data point connector. Other than the general
properties like object name and description, there are no further properties to set.
Whenever a new value is received via one of the connected input data points, the value will
immediately be forwarded to all connected output data points. This can be useful for
example to connect an internal register to a network output. If the register contains the
result of a complex calculation or is controlled by various objects across the whole project,
it is easier to have one single point of connection to the outside world, instead of connecting
the network output in parallel to the register write data point at every location where the
register is written.
It may also be used to connect input and output data points which are of similar but
incompatible types, for example receive a value from a SNVT_temp variable and output its
value via a SNVT_temp_f variable. If a structured data point should be connected entirely
to another data point of the same type, each of the structure elements needs to be connected
individually using a separate connector, because each connector is only able to handle
single values.
If the device is running firmware 4.3.0 or newer, an alternative method of connecting data
points, which also supports connections between entire data structures or connections
between different devices, is available in the data point manager dialog. See section 9 for
more information about this topic.
NOTE:
The functionality of a data point connector or any other object for which a change of an
input value causes updates to an output value without any further conditions or limits is
inherently dangerous. You must be careful not to cause endless update loops using these
types of objects. See section 14.12 for more details on this topic.
8.13 Mathematic Objects
Mathematic objects are used to do calculations on connected input data points and assign
the result to the connected output data points. The object calculates its formula every time
an update is received via one of the connected input data points, so that the output value is
always accurate. If a complex formula is used, which operates on a large number of input
Version 4.5
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