CONTREX M-Shuttle - Manual (Page 4)

CP-12 Process Ratio
The Process Ratio is the desired ratio of Follower lines to Lead lines (Follower lines/Lead lines) during
the Process Length segment of the profile.
In many applications, the Process Ratio will be the ratio that matches the Follower speed to the Lead speed during the
Process Length profile segment. If the speeds are matched, then the distance traveled will also be the same. For these
application, the Process Ratio can be calculated by determining the number of Follower lines that occur for any given
distance and dividing it by the number of Lead lines that occur for the same given distance.
The number of Lead lines for a given distance has already been entered into CP-16 for the distance in CP-15. The
Follower lines for this distance can be determined/checked using the Follower Position monitor variable MV-44 using
a similar method as the CP-16 parameter calculation:
1) Place the M-Shuttle in F-Stop.
2) Set CP-14 to either 1 or 2 (enables Follower sync).
3) Display MV-44 (Follower Position).
4) Provide a Follower Sync input by shorting the Follower Sync input to common
(J3 pin 12 to J3 pin 11). MV-44 should go to zero.
5) Move (Forward Jog) the Follower shuttle the distance specified in CP-15.
6) MV-44 should now indicate the number of Follower lines for the CP-15 distance.
Divide this number by the number entered into CP-16.
7) Return CP-14 to its original value for normal operation.
TUNING
The Tuning procedure modifies the two control algorithm parameters to achieve optimal system performance and
stability. The default tuning parameters in the M-Shuttle should provide for stable operation in the majority of
applications, but may not achieve the best possible performance for the given system. The procedure below is
provide for those applications that are either unstable or not achieving the best possible performance.
Initial tuning can be done by placing the M-Shuttle in Tune Mode (CP-14 = 6). In this mode, the M-Shuttle will move
back and forth between the Forward and Reverse Limits at the Jog speed. The two tuning parameters should then be
checked and final adjustments made while the M-Shuttle is running in the Follower Mode.
CP-65 Gain
To adjust the Gain term, first enter a value of zero into CP-66 (Integral). With the M-Shuttle running at the maximum
process speed, increase the value in CP-65 until the system starts to become unstable (instability can be observed by
erratic motion or audible disturbances). Once the point of instability is found, reduce the CP-65 value slightly until the
system stabilizes.
CP-66 Integral
With CP-65 properly adjusted and the system running at the maximum process speed, add small increases in Integral
(CP-66) while observing changes in the position error (MV-49) during the Process Length portion of the profile. As
More Integral term is added, the position error will be decreased. Adding too much Integral term will cause excessive
overshoot whereby the Follower position will go beyond the setpoint, particularly at the profile point where the
acceleration ramp meets the Profile Length. Add only enough Integral term to minimize position error without creating
excessive overshoot.
C C C C C
O N T R E X , I N C . O N T R E X , I N C . O N T R E X , I N C . O N T R E X , I N C . O N T R E X , I N C .
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