Rockwell Automation GMLC Reference Manual - Manual (Page 300)

Publication GMLC-5.2 - November 1999
Auto Correction (Configure Cam) 263
In most applications, the last registration position value should be equal to
the ideal registration position within the product cycle. If you do not
select Last Registration, the value of the last registration position upon the
occurrence of the first good registration event is undefined, in which case
the controller does not perform a phase correction. Instead, it uses the
position of this first registration event as the last registration and begins
phase correcting on the occurrence of the next (second) registration event.
Absolute Ratioed Auto-Correction
Absolute ratioed auto-correction (like absolute auto-correction)
automatically corrects for registration error, using a phase shift move of
the slave axis, upon the occurrence of every registration event. However,
with absolute ratioed auto-correction, the registration error is calculated in
registering axis (not master axis) position units and converted to master
axis units using the ratio (in feedback counts) of the master axis cycle and
registering axis cycle. This allows using the hardware registration input of
the registering axis rather than the soft registration position of the master
axis when the hardware registration input of the master axis is already
used.
When a good registration event occurs on the registering axis, the
PCAM_good_registration_count axis variable is incremented. The
absolute position (targeted position) is subtracted from the registration
position of the registering axis to determine the registration error in the
position units of the registering axis. This value is converted to the
registration error in the position units of the master axis by multiplying it
by the ratio of the master axis cycle to the registering axis cycle as shown
below.
The calculated registration error in the position units of the master axis is
then used to phase shift the slave axis via a dedicated auto-correction
indexer as shown earlier for absolute auto-correction.
Re . [ ] Re . [Re . ]
Re
g Error Master Axis g Error g Axis
Master Cycle
gistering Cycle
= Ч