Rockwell Automation Publication 2080-UM002G-EN-E - March 2015 109
Motion Control Chapter 7
Conditions for Successful Homing
For homing operation to be successful, all configured switches (or sensors) must
be properly positioned and wired. The correct position order from the most
negative position to the most positive position—that is, from the leftmost to the
rightmost in the homing setup diagrams in this section—for the switches are:
1. Lower Limit switch
2. ABS Home switch
3. Upper Limit switch
During MC_Home function block execution, the home position will be reset,
and the soft limits mechanical position will be recalculated. During homing
sequence, the motion configuration for the soft limits will be ignored.
The homing motion sequence discussed in this section has the following
configuration assumptions:
1. Homing direction is configured as negative direction;
2. The Lower limit switch is configured as enabled and wired;
The different homing modes as defined (see table Homing Modes
on page 108)
can have different, but still similar motion sequence. The concept discussed
below is applicable to various homing configurations.
MC_HOME_ABS_SWITCH
MC_HOME_ABS_SWITCH (0) homing procedure performs a homing
operation against the home switch. 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.
If axis is powered On with only one direction enabled, the MC_Home
function block (in modes 0, 1, 2, 3) will generate an error and only
MC_Home function block (mode 4) can be executed. See MC_Power
function block for more details.
If home switch is not configured as enabled, MC_HOME_ABS_SWITCH
(0) homing fails with MC_FB_ERR_PARAM.
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