Siemens OP15, Equipment Manual, Page: 52 / 177

7-2
Manual OP5, OP15
( ) J31069-D0840-U001-A2-7618
7.1 Event Messages and Alarm Messages
The process states indicated by event messages and those indicated by alarm
messages are defined during configuration. Messages on malfunctions refer-
ring to processes or states – for example,
Motor temperature too
high or Valve will not open should be categorized as alarm mes-
sages. Messages that provide information on regular processes or states, such
as
Temperature reached
or
Motor running
should be categorized
as event messages.
Apart from status messages, information on operation can also be configured
as event or alarm messages. If, for example, a machine operator wants to
start the bottling process but has forgotten to open the water intake valve on
the mixer, a message such as
Open water intake valve
can prompt
him to rectify the error.
Event and alarm messages can be configured so that any of their text compo-
nents flash to distinguish them from message text. Unacknowledged alarm
messages flash permanently.
Messages may contain static text and variable fields. The variable fields dis-
play, for example, current actual values of the PLC in numerical or symbolic
form. In addition, the date and time can also be output in messages.
If there is a condition present in the current process for a message to be is-
sued – for example, a variable has been reached – a bit is set by the PLC ap-
plication program in the data area for event and alarm messages. The OP
reads the data area after a configured polling time. In this way, a message is
detected as having ”arrived”. The bit is reset by the PLC when the condition
for issuing the message no longer exists. The message is then regarded as
having ”departed”.
Alarm and event messages are written to alarm and event buffers, respective-
ly, on the OP when they arrive. The following details are entered in the buffer
in chronological order:
times of incidents
arrivals and departures of incidents
acknowledgements of alarm messages
message numbers
values of variables at the time of arrival and departure.
Definition
Presentation
Message bit
procedure
Alarm and event
buffers
Message Handling