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106 • Chapter 6 Programming Motion DMC-1700/1800
Figure 2 Velocity (cts/sec) vs. Time (msec) Ramped Gearing
The slave axis for each figure is shown on the bottom portion of the figure; the master axis is shown on the top
portion. The shock to the slave axis will be significantly less in figure 2 than in figure1. The ramped gearing does
have one consequence. There isn’t a true synchronization of the two axes, until the gearing ramp is complete. The
slave will lag behind the true ratio during the ramp period. If exact position synchronization is required from the
point gearing is initiated, then the position must be commanded in addition to the gearing. The controller keeps
track of this position phase lag with the _GP operand. The following example will demonstrate how the command
is used.
Example – Electronic Gearing Over a Specified Interval
Objective Run two geared motors at speeds of 1.132 and -.045 times the speed of an external master. Because the
master is traveling at high speeds, it is desirable for the speeds to change slowly.
Solution: Use a DMC-1730 or DMC-1830 controller where the Z-axis is the master and X and Y are the geared
axes. We will implement the gearing change over 6000 counts (3 revolutions) of the master axis.
MO Z Turn Z off, for external master
GA Z, Z Specify Z as the master axis for both X and Y.
GD6000,6000 Specify ramped gearing over 6000 counts of the master axis.
GR 1.132,-.045 Specify gear ratios
Question: What is the effect of the ramped gearing?
Answer: Below, in the example titled Electronic Gearing, gearing would take effect immediately. From the start of
gearing if the master traveled 6000 counts, the slaves would travel 6792 counts and 270 counts.
Using the ramped gearing, the slave will engage gearing gradually. Since the gearing is engaged over the interval of
6000 counts of the master, the slave will only travel ~3396 counts and ~135 counts respectively. The difference