NOTE:
When the width is more 99.75 mm the display will only show one decimal place even though the
nominal width can be set to any multiple of 0.25 mm. Similarly when the nominal width is more than 999.75
mm the display will only show integer values. However, if the nominal width is incremented by 0.25 mm
increments, the controller will still record those without displaying the decimal places.
Upper Limit
When the measured web width is more than the nominal web width then the width error is positive. With
an appropriate output on the SCU5 controller a fault signal can be generated when the positive width error is
more than the upper limit. If the error is equal to the upper limit, no fault signal would be generated.
NOTE:
The controller will not check to see if the upper limit is more than the nominal width.
NOTE:
The minimum value for the upper limit that can be set is 1 mm and the maximum value is 99.75 mm.
Lower Limit
When the measured web width is less than the nominal web width then the width error is negative. With an
appropriate output on the SCU5 controller a fault signal can be generated when the negative width error is
less than the lower limit. If the error is equal to the lower limit, no fault signal would be generated.
NOTE:
The controller will not check to see if the lower limit magnitude is more than the nominal width.
NOTE:
The minimum value for the lower limit that can be set is 1 mm and the maximum value is 99.75 mm.
Measured Width
The measured width provides a real time width value based on the image captured by one or two sensors.
The measured width is the sum of raw measurement from each sensor plus any offset. Offset is often
necessary when the width is measured with two sensors. Since the controller does not know the actual
distance between the two sensors, the offset is necessary to compute the measured width based on the raw
width measurement from the sensor(s).
NOTE:
The measured width will update only with correct settings. For example, if one sensor is connected
and the sensor is set to left mode, the measured width value will not update.
One Sensor
When one sensor is used for width measurement, the sensor should be wide enough to see both the edges
of the web even when the web wanders in the cross-machine direction (width wise movement). The sensor
mode should be in edge mode with the sensor configuration to be in center to see both the edges. The
measured width is the raw width plus the offset. The offset is still valid for one sensor however it may be a
small value. The offset is used to compensate for working distance and focus corrections.
Two Sensors
When two sensors are used for width measurement, each sensor should be installed with appropriate
orientation, i.e., one sensor should see the left edge of the web and the other the right edge. For most
applications the sensor mode should be in edge mode. The measurement from each sensor is the amount of
web seen by each sensor, which is the raw width. If the two sensors are exactly butted against each other
Content subject to change without notice
SCU5: Sensor and Web Guide Controller User Manual v 3.6| Page 33
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