User Manual
Chapter 8
GFK-1742F
Jan 2020
Follower Motion
230
master velocity, they will be inserted during make-up distance correction motion. This
motion has an automatically calculated trapezoidal velocity profile determined by the
Follower Ramp Distance Makeup Time, the amount of accumulated counts, and the
configured Follower Ramp Acceleration. Set the Follower Ramp Distance Make-up Time to
the desired time in the configuration software or it can be changed with the host controller
%AQ Command 42h.
If the Follower Ramp Distance Makeup Time is too short, then the automatically generated
velocity profile is triangular in profile. If during the distance correction velocity exceeds 80%
of the configured Velocity Limit, then the automatically calculated move velocity will be
clamped at 80% of the limit value. Clamping the makeup move velocity at 80% of the
velocity limit allows the system some reserve velocity capacity for continued tracking of the
master source velocity. In both cases a warning message is reported, and the real distance
make-up time is longer than programmed, but the distance is still corrected properly.
Setting a Follower Ramp Distance Make-Up Time of 0 allows the Ramp feature to accelerate
the axis without making up any of the accumulated counts. In this instance velocity will not
exceed the master velocity. For applications where lost counts do not matter, set the
distance make-up time = 0.
By default, the superimposed motion profile that is automatically generated by the follower
ramp function (with non-zero makeup time) is trapezoidal using the Follower Ramp
Acceleration and a distance derived from the active Ramp Makeup Time.
The value of the Velocity Limit may affect functionality differently depending on the
relationships of the master source velocity. The following case examples illustrate these
points.
Case 1: The master source velocity is less than 80% of the configured Velocity Limit and the
makeup time (Mkup Time) is a long enough interval so that the resultant velocity remains
less than 80% of the Vlim. This is the preferred operation; no errors are reported, and the
over speed move of the ramp function occurs within the specified makeup time. The
follower axis velocity will not exceed 80% of the Vlim unless the master source velocity
increases.
Case 2: The master source velocity is below 80% of the configured Velocity Limit but the
makeup time interval is too short to allow operation as in case 1. A status only error (ECh)
will be returned when the follower velocity matches the master command velocity. The
makeup move will accelerate using the active Follower Ramp Acceleration to 80% of the
velocity limit (Vlim). The makeup move will occur, and all accumulated counts stored during
initial acceleration will be used.
Case 3: The master source velocity is greater than 80% of the configured Velocity Limit when
the follower velocity matches the master command velocity. A status only error (EAh) is
returned and no makeup correction move is attempted.