Siemens SINUMERIK Commissioning Manual page 495

Acknowledgment
An HMI system acknowledgment is divided into two steps:
● In the first step, the HMI software transfers the control information 255 to DB19.Byte10.
● In the second step, the actual acknowledgment takes place on the PLC in which
This is necessary in order that, despite the lack of synchronism between the HMI and the
PLC, the same key code transferred twice in immediate succession can be detected by the
HMI. This defined virtual key activation enables the HMI to identify every PLC key sequence
uniquely. The control information is of no significance to the PLC program (transparent) and
must not be changed.
Next key input
If the transfer byte is set to 0, the PLC program can specify a new key. The current key
request is processed in parallel in the HMI system. The request leads to a switchover to the
corresponding task or initiates a state/action command in the current task.
If the task switchover cannot be executed, the operator interface will send a message to
indicate this.
Requirements of the PLC program
A new request can only be set if the HMI system has acknowledged the previous request (0
in the interface). If the PLC program is deriving the key from a machine control panel key or
from another source, it must provide sufficient intermediate storage for the key to ensure that
no data is lost if the key is pressed very quickly.
Selecting dialogs from PLC
There is an interface between the PLC and HMI Embedded sl for selecting dialogs. These
PLC dialogs offer the same means of display and functions as for the dialogs selected via
the softkeys.
4.3.2 Description of the PLC display selection
Description of the interface
The interface contains the display number, control bits from the PLC to the HMI and control
bits from the HMI to the PLC. The interface requires a total of 8 bytes in DB19, 4 bytes for
each HMI Embedded sl.
Because each NCU can be addressed by up to two HMI Embedded sls at the same time in
systems with "multiple operator panel fronts and multiple NCUs", this interface can exist in
duplicate.
References: /FB2/, "Multiple operator panel fronts and multiple NCUs" (B3)
Expanding the user interface
Commissioning Manual, 11/2006, 6FC5397-0DP10-0BA0
DB19.Byte10 is cleared.
Configure hotkeys and PLC keys
4.3 PLC interface
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