Nexen RSD250 964260 - Manual (Page 9)

9 FORM NO. L-21179-D-1108
A typical unwind application begins with a new full roll. To
insure that the dancer arm stabilizes as quickly as pos-
sible, the SPLICE signal can be used to reset adaptation
to NEW ROLL ADAPTATION before the machine starts.
This shortens the time it takes for the RSD250 to adapt
its gains to the new roll.
If a SPLICE signal is not used, the dancer arm may be
sluggish on the first start with a full roll. This is because
the adaptation process will begin at a minimum adapta-
tion value and take longer to reach the optimum gain level.
Once the RSD250 adapts to the new roll, the adaptation
process will level off and on subsequent starts the arm
will quickly move into position. During a run, the adapta-
tion process continually adjusts the gains to account for
changes in roll size.
When the START signal goes high at the Start/Stopped
input, the RSD250 will begin adapting. The web must
begin to move at this instant.
TUNING
As the roll begins to accelerate, the dancer arm will seek
its home position. Over time the roll will decrease in size
along with RSD250’s output and control gains. During
constant speeds the dancer arm will remain stable, but the
output signal will not be steady. During a machine stop,
the adaptation process will increase the RSD250’s output
and gains in order to overcome the roll’s inertia.
When the RSD250 is in STOPPED mode, the adaptation
process is halted. However, the RSD250’s output will still
change depending on the dancer arm’s position. After the
next START signal is given, the RSD250 adaptation will
begin adapting again.
Any time the SPLICE signal is given, the adaptation pro-
cess will be reset to NEW ROLL ADAPTATION. This is
useful after a web break where the adaptation process
could increase the RSD250’s gain too high resulting in
an unstable dancer arm at the next machine start. It can
also be reset to the minimum adaptation value by moving
the dancer arm to its maximum storage position while the
RSD250 is stopped.
Small Roll Large Roll
Acceleration Acceleration
Run Speed Run Speed
Deceleration Deceleration
Stopped
Start/Stopped Signal
Splice
Signal
New Roll Adaptation
Min. Adaptation
Optimum Gain
Reached
Adaptation
Figure 5
NOTE: Only GAIN and NEw ROLL ADAPTATION can be adjusted via potentiometers on the RSD250’s printed
circuit board. For access to all RSD250 setup and tuning parameters, you must use the RSD Communications
Software Kit. If using the RSD Communications Software, jumper w2 must be in the one position (Refer to the
RSD200 maintenance manual).