CALIBRATION ALTERNATIVES
AUTO ZERO
This feature automatically performs a Zero calibration, whenever material flow ceases in the RUN mode.
If the Auto Zero feature is desired, provide a dry contact input to the CompuScale III terminals TB1-34 and
TB1-37. The contact may be activated by a material feed controlling device such as a motor control, material
control gate, or valve. The contact must be closed when the material feed is stopped.
When the contact is closed, and the belt is running empty (within 4% of span from the current zero reference)
[AUTO ZERO IN PROGRESS] is displayed in the AUX 2 field. The time required for completion is dependent
upon Belt Speed (P4), Belt Length (P6), and Calibration Duration (P30). The number of full belt revolutions
remaining before completion is displayed in the BELT REV field.
When complete, the Auto Zero is compared to the last operator Zero.
If the Auto Zero is within 2% of span from the last operator zero, the CompuScale III briefly displays
[CALIBRATION COMPLETE] in the AUX 2 field and the deviation from the current zero reference in the
VALUE field. The Auto Zero is automatically accepted and RUN mode operation continues.
Otherwise, the Auto Zero results are rejected, and operation continues with the previous zero reference.
CERTIFICATION MODE
In this mode, parameters may be accessed for viewing. However, if a parameter value alteration is attempted,
the alteration is not permitted and [CERTIFICATION LOCKOUT] is displayed in the AUX 2 field.
To activate the Certified Mode, close SW1 contact 6 (SW1-6) after the CompuScale III is programmed and
calibrated.
The maximum acceptable deviation between the last Zero performed by the operator (before closing this
contact) and any subsequent Zero, is limited to 2% of span. Span calibrations are not permitted in this mode.
ALTERNATE TEST REFERENCES
For most applications, a Test Weight is applied to the belt scale to simulate a material load for the Span
calibration. Alternatively, a Test Chain or
ECAL
(CompuScale III internal reference) may be used for this
purpose. A Test Chain may be recommended when performing material tests would be extremely
inconvenient or impractical. ECAL is normally used when applying a Test Weight or Test Chain is impractical
(especially when the belt scale is installed in a hazardous area).
When a Test Weight or Test Chain is used exclusively, Test Reference selection (P20) is not required.
Typically, when more than one Test Reference is utilized, one reference is considered the
Primary Reference
and the alternate reference(s) are considered the
Secondary Reference(s)
. After accepting the results of a
Span calibration utilizing the Primary Reference (or after performing a Span Adjust), the Secondary
Reference(s) should be selected (P20) and Factored (P9). Refer to Parameters/P7,P8,P9, and P20.
When the ECAL reference is selected (P20=1), ECAL is automatically applied when a Span calibration or
Factoring (P9) is activated, and removed when the process is complete or aborted. When the ECAL reference
is on, [ECAL] is displayed in the ECAL field.
PL-367
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