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IM-S51-07 CTLS Issue 1
SP7-10, SP7-11, SP7-12 and SP7-20, SP7-21, SP7-22 Parameterization
The "tolerance band" TOL_BAND defines a ± range around the position setpoint. When the position of the valves and fittings
reaches this range, the parameter set of the positioner is toggled to a different algorithm that is used to continue with a slow
controlling action until the dead band DEADBAND is reached. The system is only considered balanced once the sensitivity
range is reached (see parameter ADJ_MODE)
Input value in steps of 0.1%
3.11.6 Y-OFS DN – Offset (down)
NOTE
In the case of most actuators, all control parameters can be optimized by using Auto Adjust. Changes should
only be made when auto adjust cannot be executed or control stability cannot be achieved.
The "offset for the setpoint signal" linearizes the behavior of the I/P module used and enables rapid compensation even in the case
of small control deviations. The value is limited at the lower end by a minimum value (neutral zone).
The offset significantly affects the control speed for control deviations of less than 5 %.
In manual modes MANUAL and MAN_SENS, the offset values are issued to the I/P module for fine adjustment. For larger, slower
actuators Autoadjust may determine values higher than 80 %. In these cases there will be no noticeable difference between fine and
coarse adjustment while in manual mode.
To compensate for existing asymmetries in the controlled system, the offset should be configured separately for both
positioning directions (up / down).
For most actuators, a satisfactory control response is achieved with offset values in the 40 ... 80 % range. If, in the event of setpoint
changes, the control behavior demonstrates an overshoot of less than 2 %, both offset values should be decreased.
Both offset values should be increased when the actuator stops outside the tolerance band. Use the parameter Y-OFS DN to adjust
the Y offset for the downward positioning direction (towards 0 %).
3.11.7 TOL_BAND – Tolerance band
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