Rockwell Automation Publication 2080-UM002N-EN-E - November 2022
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Chapter 9 Motion Control
Scenario 2: Moving part on Lower Limit 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
Lower Limit switch On->Off edge;
2. Once Lower Limit switch On->Off edge is detected, record the position as mechanical
home position, and decelerate to stop;
3. Move to the configured home position. The mechanical home position recorded during
moving right sequence, plus the home offset configured for the axis through the
software.
Scenario 3: 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_WITH_ABS
MC_HOME_REF_WITH_ABS (2) homing procedure performs a homing operation against Home
switch, plus fine Ref Pulse signal. The actual motion sequence is dependent on the home
switch, 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 Home 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 Home Abs switch is detected, the moving part decelerates to stop;
3. Moving part moves back (in positive direction) in creep velocity to detect Home Abs
On->Off edge;
4. Once Home Abs switch On->Off is detected, start to detect first Ref Pulse signal coming
in;
5. Once the first Ref Pulse signal comes, record the position as 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.
Scenario 2: Moving part between Lower Limit and Home 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 Home switch
On->Off edge;
4. Once Home Abs switch On->Off is detected, start to detect first Ref Pulse signal;
5. Once the first Ref Pulse signal comes, record the position as mechanical home position,
and decelerate to stop.
IMPORTANT
If Home switch or Ref Pulse is not configured as Enabled,
MC_HOME_REF_WITH_ABS (2) homing fails with Error ID:
MC_FB_ERR_PARAM.