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7
Events Menu
Introduction
An event is a special message that is generated on the card asynchronously.
This means that it is not the response to a request to the card, but a
spontaneous message.
What is the Goal of
an event?
The goal of events is to inform the environment about a changing condition
on the card. A message may be broadcast to mark the change in status. The
message is volatile and cannot be retrieved from the system after it has
been broadcast. There are several means by which the message can be
filtered.
Events
The events reported by the card are as follows;
Announcements
Announcements
is not an event. This item is only used for switching the
announcement of status changes on/off. 0=off, other =on
What information is
available in an
event?
The message consists of the following items;
1)
A message string to show what has happened in text, for example:
“INP_LOSS”, “REF_LOSS”, “INP_RETURN”.
2)
A tag that also shows what happens, but with a predefined number: e.g.
1 (= loss of input), 2 (= loss of reference), 129(= 1+128 = return of
input). For a list of these predefined tags see the table on the next page.
3)
A priority that marks the importance of an event. This value is defined
by the user and can have any value between 1 and 255, or 0 when
disabled.
4)
A slot number of the source of this event.
The Message String
The message string is defined in the card and is therefore fixed. It may be
used in controlling software like Cortex to show the event.
The Tag
The tag is also defined in the card. The tag has a fixed meaning. When
controlling or monitoring software should make decisions based on events,
it is easier to use the tag instead of interpreting a string. The first
implementation is the tag controlled switch in the GPI16.
In cases where the event marks a change to fault status (e.g. 1 for Loss of
Input) the complement is marked by the tag increased by 128 (80
hex
) (e.g.
129 (81
hex
) for Return of Input).
