L-VIS User Manual
160
LOYTEC
Version 6.2
LOYTEC electronics GmbH
9.11.1 Alarm Generator Properties
Once all inputs and the output are connected, the alarm generator may be configured on the
Alarm Generator
property page. For each of the connected inputs, an independent set of
parameters is required. The available input points are listed in the top left area of the
property page.
NOTE:
If logic or arithmetic operations are required to determine an alarm condition (for example
signal an alarm when T1 > T2), a mathematic object is required to conduct the required
operations. The result, which is conveniently stored into an internal register, is then
monitored using the alarm generator.
The suggested workflow to configure the alarm generator is as follows:
First, select the input point for which the monitoring rules should be configured.
Define the
Alarm Condition
using the radio buttons at the bottom left of the page.
The available choices allow basic monitoring functionality and always define the
condition, under which the alarm should be SET. If the value no longer satisfies
the condition, the alarm will be cleared. To filter out spikes, it is usually good to
set an amount of time which the alarm condition needs to be satisfied, before the
alarm is actually set. The default of one second is often a reasonable value.
Define the
Data Point Value Range
. Depending on your choice for the condition,
you may need to enter values either for both (minimum value and maximum
value) or only for one of the two. If your condition is inside or outside range, you
need to enter both values to define the range, for the condition ‘above max’ only
the maximum value is required and for the condition ‘below min’ only the
minimum value needs to be filled in.
Define the
Action
that should be taken. The basic choice here is to have the alarm
generator SET the alarm when the condition is satisfied and also CLEAR the
alarm when the condition is no longer satisfied. However, you may want to only
SET the alarm when the condition is met and not clear it again, because you may
require the user to manually clear the alarm later. In this case, use the ‘set on
alarm enter’ action, which will only set the alarm, but will never clear it. To
actually clear the alarm, you can either use other means to update the alarm
output variable, or you can have a separate input on your alarm generator and
define a rule for this input, which will eventually clear the alarm, using the ‘clear
on alarm leave’ action.
As the last step, define the desired output, either for both conditions (set and
clear) or for only one of them. The required input fields will be active, while the
other ones will be grayed out. Note that the description field may currently only
contain ASCII characters.
The above procedure needs to be repeated for all connected input data points.
9.11.2 Application Hints
While it is pretty straight forward to configure a simple alarm generator to output an alarm
when for example a temperature reaches a certain maximum value, the alarm generator can
be used for more complex applications as well. Two of the most often used applications are
described in more detail in the next sections.
9.11.2.1 Alarm Condition with Hysteresis
Consider you want to issue an alarm when a temperature rises above T1, but the alarm
should not be cleared unless the temperature falls below T2, which would be less than T1.
Similar to a thermal protection which, once it activates, turns off the device and does not
