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Rockwell Automation Publication 2080-UM002N-EN-E - November 2022
Chapter 9 Motion Control
6. Move to the configured home position. The mechanical home position recorded during
moving back sequence, plus the home offset configured for the axis through the
Connected Components Workbench software.
Scenario 3: Moving part on Lower Limit or Home switch before homing starts
The homing motion sequence for this scenario is as follows:
1. Moving part moves to its right side (in positive direction) in creep velocity to detect
Home switch On->Off edge;
2. Once Home Abs switch On->Off is detected, start to detect first Ref Pulse signal;
3. Once the first Ref Pulse signal comes, record the position as mechanical home position,
and decelerate to stop;
4. Move to the configured home position. The mechanical home position recorded during
moving right sequence, plus the home offset configured for the axis in the Connected
Components Workbench software.
Scenario 4: Moving part at left (negative) side of Lower Limit switch before homing starts
In this case, the homing motion fails and moves continuously to the left until drive or moving
part fails to move. User needs to make sure the moving part is at the proper location before
homing starts.
MC_HOME_REF_PULSE
For Homing against Lower Limit switch, one positive home offset can be configured; for
Homing against Upper Limit switch, one negative home offset can be configured.
MC_HOME_REF_PULSE (3) homing procedure performs a homing operation against Limit
switch, plus fine Ref Pulse signal. The actual motion sequence is dependent on the limit switch
configuration, and the actual status for the switches before homing starts—that is, when the
MC_Home function block is issued.
Scenario 1: Moving part at right (positive) side of Lower Limit switch before homing starts
The homing motion sequence for this scenario is as follows:
1. Moving part moves to its left side (in negative direction);
2. When Lower Limit switch is detected, the moving part decelerates to stop, or stops
immediately, according to Limit Switch Hard Stop configuration;
3. Moving part moves back (in positive direction) in creep velocity to detect Lower Limit
switch On->Off edge;
4. Once Lower Limit switch On->Off edge is detected, start to detect first Ref Pulse signal;
5. Once the first Ref Pulse signal comes, record the position as the mechanical home
position, and decelerate to stop;
6. Move to the configured home position. The mechanical home position recorded during
moving back sequence, plus the home offset configured for the axis through the
Connected Components Workbench software.
IMPORTANT
In this case, if Lower limit switch is not configured, or not wired, the
homing motion will fail and moves continuously to the left until the drive
or moving part fails to move.
IMPORTANT
If Lower Limit switch or Ref Pulse is not configured as Enabled,
MC_HOME_REF_PULSE (3) homing fails (ErrorID: MC_FB_ERR_PARAM).