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Response time
Bytes n+3 and n+4 must be scanned on the PLC side within a second and cyclically. This
ensures that no more than 256 pulses can be added between two scans of the handwheel.
For 256 pulses, approximately 4.5 revolutions of the handwheel are required.
The rotary pulse encoder supplies a maximum of 200 pulses per second.
Notice
The input pulses should take effect immediately on the PLC and cause a response in the
system. Therefore, set up a scan cycle <= 100 ms in the PLC to achieve this.
A.2.3
Evaluating operator control elements via WinCC flexible system functions
A.2.3.1
LED control of the softkeys
Application
LEDs are integrated in the softkeys F1 to F8 of the Mobile Panel 177. The integrated LEDs
can be activated by the controller.
The LED can assume the following states:
• Off
• Slow flashing
• Rapid flashing
• On
This allows the LED to signalise to the operatorthat he should press the softkey in an active
project.
Bit assignment
The following table shows the bit assignment for the LED tag of the softkey LEDs:
Mobile Panel 177 (WinCC flexible)
Operating Instructions (Compact), Edition 07/2005
Bit n+1
0
0
1
1
A.2 Evaluation of the operator control elements
Bit n
LED status
0
Off
1
Rapid flashing
0
Slow flashing
1
On (continuous)
Appendix
A-9
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