Rockwell Automation 2080-LC50 Micro830 and Micro850 Programmable Controllers User Manual - Manual (Page 120)

106 Rockwell Automation Publication 2080-UM002F-EN-E - December 2013
Chapter 7 Motion Control with PTO and PWM
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.
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.