Siemens simatic hmi op7 Equipment Manual page 61

Standby message
Alarm and event
buffers
Overflow warning
Equipment Manual OP7, OP17
Release 04/99
A sub-category of the event message is the standby message. The standby
message is the event message number 0. It appears on the display when the
OP is operating at the message level and event or alarm messages are not
waiting.
The standby message is stored in the firmware and contains the version and
the device type – for example
OP7
4 x 20 char.
Figure 7-1 Example of Standard Standby Message on OP7
Depending on the configuration, the standby message can be represented by
other text – for example a company logo. It can contain the date and time but
not tags.
Alarm and event messages are written to alarm and event buffers, respective-
ly, on the OP when they arrive.
The message buffer of the OP can store up to 256 events. Events are the:
arrival of a message,
acknowledgment of a message,
departure of a message.
The following details are entered in the buffer in chronological order:
incident of events
arrival, departure and achnowledgement
message numbers
values of tags at the time of arrival and departure.
During configuration, you can define a remaining buffer space. When this
remaining buffer space has been reached, an automatic overflow warning is
issued – for example
EM remaining buffer.
Messages continue to be inserted into the buffer even after the remaining
buffer space has been reached.
Vx.xx
7-3