Siemens SINUMERIK 840D sl Commissioning Manual page 206

Optimize the drive.
11.4 Servo trace
"Threshold" input field
Direct input of the trigger threshold.
The threshold is only effective with trigger types "Positive edge" and "Negative edge".
The unit refers to the selected signal.
Softkeys "Axis+" and "Axis-"
Selection of the axis/spindle when the cursor is positioned on the appropriate "Axis/spindle
name" list field.
You can also select the axis/spindle directly in the list box from the drop-down list using the
cursor.
Softkeys "Start" and "Stop"
With the "Start" softkey, trace function recording is started.
With the "Stop" softkey or RESET, you can cancel a running measurement.
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Commissioning Manual, 07/2007, 6FC5397-2AP10-3BA0
IBN CNC: NCK, PLC, drive