Rockwell Automation GMLC Reference Manual - Manual (Page 299)

Publication GMLC-5.2 - November 1999
262 Motion Blocks
To allow rejecting spurious registration events, a tolerance may be
specified around the nominal length by selecting Tolerance, and entering
a value or expression equal to the desired nominal length tolerance in the
data entry box. The specified tolerance is interpreted as a ± quantity
around the specified nominal length and used to distinguish good
registration events from bad ones, as shown below.
As shown above, the first registration event that occurs within the
specified tolerance is considered the good registration. All registration
events that occur after a good registration event and before the beginning
of the next tolerance area are considered bad, even if they occur within
the current tolerance. If Tolerance is not selected, all registration events
on the registering axis are considered good.
Last Registration
When you first enable relative auto-correction, it is often necessary to
have a default value for the last registration position (see the figure earlier
in this section) to ensure a reasonable registration distance calculation
upon the occurrence of the first registration event.
To specify such a default last registration position, select Last
Registration, and enter the desired value or expression, in the position
units of the master axis, into the corresponding field.
Tolerance
Axis Position
+ –
Programmed
Tolerance
Value
Registration
Input
Last
Good
Registration
Nominal Length
Bad
Registrations
Bad
Registrations
Good
Registration