Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual - Manual (Page 407)

Publication 1784-UM003A-EN-P – June 2003
Motion Object Attributes 399
For example, specifying a position error tolerance of 0.75 Position Units
means that a Position Error Fault will be generated whenever the position
error of the axis is greater than 0.75 or less than -0.75 Position Units, as shown
below:
Figure 13.25 Position Error
The self tuning routine sets the position error tolerance to twice the following
error at maximum speed based on the measured response of the axis. In most
applications, this value provides reasonable protection in case of an axis fault
or stall condition without nuisance faults during normal operation. If you need
to change the calculated position error tolerance value, the recommended
setting is 150% to 200% of the position error while the axis is running at its
maximum speed.
Position Lock Tolerance The Position Lock Tolerance attribute value specifies how much position error
the SERCOS module tolerates when giving a true Position Locked Status
indication. When used in conjunction with the Position Locked Status bit, it is
a useful parameter to control positioning accuracy. The Position Lock
Tolerance value should be set, in Position Units, to the desired positioning
accuracy of the axis.
The position lock tolerance value is interpreted as a ± quantity. For example, if
your position units are Inches, specifying a position lock tolerance of 0.01
provides a minimum positioning accuracy of ±0.01 inches as shown below.
Figure 13.26 Position Lock Range
GSV/SSV Access Attribute Name Data Type Values
SSV/GSV Position Lock Tolerance REAL
Position Units