Siemens SIMATIC HMI OP3, Equipment Manual

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11-4
Operator Panel OP3
Edition 11/99
11.3 Evaluating Screen Numbers
The screen number area is located on the PLC. The OP3 writes the number of
the current screen to this area. If the PLC writes a screen number to the
screen number area, the screen is opened on the OP3. You can configure
operator guidance in this way.
If the screen number area is to be used, it must be specified during
configuration as the area pointer and created on the PLC. Figure 11-5 shows
the construction of the screen number area.
Entry number
7.. ..0 7.. ..0
1st word
Entry number Screen number
2nd word
Screen number
Bit 7 = 1: ID for special screen
Figure 11-5 Construction of the Screen Number Area on the PLC
The screen number area consists of two consecutive data words. The first
data word is used by the OP3 to store information about the display contents
(screen number and entry number).
If the PLC stores screen numbers and entry numbers in the second data word,
the display of a specific screen or a specific screen entry is initiated on
the OP3.
The hexadecimal value FFFF in the first or the second data word indicates
the message level; a value of 0 in the second data word indicates enabling of
OP3 operation.
0xFF is written to the screen number area when the OP3 jumps to message
level; on its return, the number of the last screen called is sent once more.
Application
Configuring
screen
number area
Automatic change
to message level
Process-Dependent Operator Guidance