Messages - Siemens SIMATIC HMI TP 170A Equipment Manual

5.3

Messages

What are messages?
Messages which appear on the operating unit indicate events and statuses related
to the control process and operating unit itself. A message can contain text and
tags.
The operating unit differentiates between event messages and system messages:
Event messages
indicate the status in a process, e.g. Motor ON.
Event messages are configured. They are triggered when a bit is set in the
PLC.
System Messages
are triggered by the operating unit. They do not have to be configured.
System messages indicate incorrect operations or communication faults, for
example. A time period can be considered for system messages in the
configuration software. This defines how long a system message appears on
the operating unit.
A list of the most important system messages is provided in the Appendix C.
Message events
These messages are triggered according to events. Message events on the
TP 170A include:
Message arrival
A message which has been triggered is considered as having arrived. As soon
as message is triggered, it is displayed in the operating unit message display
and is then considered as queued.
Message departure
A message is considered as having departed when its configured time period
has expired or the event causing the message is no longer present. As soon as
a message has departed, it is deleted from the message display.
TP 170A Equipment Manual
Release 12/99
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