Rockwell Automation Publication 2080-UM002L-EN-E - November 2021 115
Chapter 7 Motion Control
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 Puls
e
si
gnal 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 positi
on
recorded during moving
back sequence, plus the
home offset configured
for the axis through the Connected Compone
nts 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 dece
lerates to
stop, o
r 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 Puls
e
si
gnal;
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 positi
on
recorded during moving
back sequence, plus the
home offset configured
for the axis through the Connected Compone
nts 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;
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.
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.
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