Rockwell Automation GMLC Reference Manual - Manual (Page 253)

Publication GMLC-5.2 - November 1999
216 Motion Blocks
Specifying the gear ratio as a fraction allows the use of irrational numbers
(such as
1 /
3
) as gear ratios, with no accumulated positioning errors or
round off. Because the master and slave count values do not use the axis
conversion constants, and because they are integers, the actual gear ratio
relationship between the slave and master axes exactly matches the
specified ratio.
For example, the irrational gear ratio 1 /
3
can be specified as 1 slave count
to 3 master counts, 10 slave counts to 30 master counts, 3 slave counts to
9 master counts, etc.
Ramping to Master Speed
If you select Ramp to Master Speed, the slave axis accelerates or
decelerates to gearing speed (i.e., to the speed the slave axis would be
moving if it were geared to the selected master axis, given the specified
gearing ratio) using a trapezoidal profile. This causes linear acceleration
or deceleration. Once the slave axis has reached gearing speed, electronic
gearing is automatically activated according to the other selections.
Enter a value or expression for the acceleration rate, either as a percentage
of the maximum acceleration rate, or in the slave axis position units per
second
2 .
Ramping provides an electronic clutch that smoothly engages the slave
axis to the master axis, as shown below.