Direction Reversal At The Hardware Limit Switch (Reversing Cam) - Siemens SIMATIC S7-1500 Function Manual

Motion sequence
The motion occurs in the following sequence:
1. Enablement of passive homing via the Motion Control instruction "MC_Home".
2. Motion due to a Motion Control job from the application
3. Detection of the homing mark
3.14.10

Direction reversal at the hardware limit switch (reversing cam)

During active homing, the hardware limit switch can optionally be used as a reversing cam. If
the homing mark is not detected or the motion was not in the homing direction, then the
motion continues after the reversing cam in the opposite direction with the approach velocity.
When the hardware limit switch is reached, the dynamic defaults become effective.
Deceleration with the emergency stop deceleration does not occur.
NOTICE
Avoid moving to a mechanical endstop
Ensure by one of the following measures, that in a direction reversal the machine does not
move to a mechanical endstop.
• Keep the approach velocity low.
• Increase the configured acceleration / deceleration.
• Increase the offset between the hardware limit switch and the mechanical endstop.
S7-1500 Motion Control V13 Update 3
Function Manual, 07/2014, A5E03879256-AC
The detection of the homing mark at the digital input is enabled when the actual position
value of the axis or encoder moves in the assigned homing direction.
In the example, the falling edge of the switch at the digital input represents the homing
mark.
When the homing mark is detected, the position of the axis or encoder is set depending
on the configured mode:
– Parameter "Mode" to "MC_Home" = 2, 8
Position = value in parameter "Position"
– Parameter "Mode" to "MC_Home" = 10
Position = value in tag <TO>.Homing.HomePosition
Note
Parameter "MC_Home.Mode"
The "MC_Home.Mode" parameter for S7-1200 Motion Control and S7-1500 Motion
Control has been standardized within the framework of technology version V2.0. This
results in a new assignment of the parameter values for the "MC_Home.Mode"
parameter. A comparison of the "MC_Home.Mode" parameter for technology versions
V1.0 and V2.0 is available in the section Version overview (Page 86).
Basics
3.14 Homing
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