Overflow Of The Message Buffer; Message Priorities - Siemens SIMATIC PCS 7 Service Manual

6.5.5

Overflow of the message buffer

Overflow of the message buffer
Each component of the overall PCS 7 system can process only a limited number of messages.
If messages generated in a component (for example, an AS) within a given time frame are
more than it can process, some of these messages will be lost. If this case, the AS sets an
overflow flag and the following event is reported at the PCS 7 OS: "NRMS7 Messages Lost".
Note
If events that trigger messages change their status in very quick succession, this can trigger
a message surge. The overview of the plant status can no longer be sufficiently ensured.
Additional information
You can prevent a message surge by activating the "Messaging Triggered by
Acknowledgment" function. You can find information on configuring in the configuration manual
Process Control System PCS 7; Engineering System.
6.5.6

Message priorities

Changing the message priorities
Each message can be assigned a priority in PCS 7. Here, "0" represents the lowest priority
and "16" the highest priority. When creating a new signaling block, these messages initially
have the lowest priority ("0").
You can change the message priority in different ways:
● Via the object properties of the block
● Via the process object view
● Via the import
Rules
●
"CPU-oriented unique".
● In the PCS 7 OS, the unacknowledged message with the highest priority is always shown
in the message line above the overview. If there are several messages have the same
priority, this is always the last in.
● You can filter by priority within the message list.
Service Support and Diagnostics (V8.2)
Service Manual, 03/2016, A5E36200111-AA
Message priorities can only be specified if you defined the message number range as
Message concept of PCS 7
6.5 Understanding messages
77