Technical data

Configuring Messages
16.2 Project-Oriented Message Configuration
Programming with STEP 7
352 Manual, 05/2010, A5E02789666-01
16.2.3 Assigning and Editing Symbol-Related Messages
16.2.3.1 How to Assign and Edit Symbol-Related Messages (Project-Oriented)
Symbol-related messages (SCAN) are assigned directly to a signal in the symbol table. Permitted
signals are all Boolean addresses: inputs (I), outputs (Q), and bit memory (M). You can assign
these signals different attributes, messages texts, and up to 10 associated values with the
message configuration function. You can make it easier to select signals in the symbol table by
setting filters.
With a symbol related message you can scan a signal in a predefined time interval to determine
whether a signal change has taken place.
Note
The time interval is dependent on the CPU used.
Basic Procedure
During processing, the signals for which you have configured messages are checked
asynchronously to your program. The checks take place at the configured time intervals. The
messages are displayed on the assigned display devices.
Caution
If you want to assign or edit symbol-related messages and, during the same work procedure, you have
previously copied symbols between two symbol tables, you will then have to first close the symbol
table that you no longer need to work in. Otherwise, you will not be able to save your message
configurations. Under certain conditions, the last entries made in the message configuration dialog will
be lost.