Digi DC-190 installation manual Scale Operations, Entering Tare Weights

6.0Scale Operations

The following sections contain detailed operator instructions for the DC-190 counting scale. Included are instructions to enter tare weights, toggle between net and gross weight, enter unit weights, perform inventory accumulation and reduction, and toggle between scales. All operator functions are conducted with the scale in the weighing or normal mode. See Section 7.0 on page 30 for information about scale programming.

Counting scale accuracy is primarily determined by the following factors:

•Sample size (number of pieces)

•Total sample size as a percentage of full scale capacity

•Piece-to-piece weight variation

As a general rule when determining sample size of fairly uniform pieces, the larger the sample size the greater the total sample weight, therefore, the better the counting accuracy. Selecting the smallest capacity scale that can obtain the highest counting resolution should be considered, but should not sacrifice the capacity required for the heaviest container of parts. For this specific application, a dual-platform scale may be the best selection.

There is a direct relationship between piece-to-piece weight variation (non-uniformity) and counting accuracy. Therefore, elimination of the piece-to-piece weight variations can be accomplished by:

1.Isolating the sample used to calculate the unit weight and use the same sample to re-check the scale.

2.Recalculating the unit weight from lot-to-lot of parts. Parts manufactured on one machine may vary slightly from another machine relative to weight.

3.Tightening the manufacturing tolerances on the parts reduces piece weight variations and increases count accuracy.

6.1Entering Tare Weights

Tare weights can be entered in the scale by one of two methods: one-touch tare or digital tare.

NOTES:

•SPEC 27, bit 2 (Digital Tare Setting) must be a 1 to allow digital tare.

•SPEC 27, bits 0 and 1 (Tare Range) must be set to the appropriate tare range value. Default is 00, 100 percent of full scale.

One-Touch Tare, Tare Weight Unknown

1.If the tare weight value is not known, place the container, box, or item to be tared on the scale and press TARE. The WEIGHT display should now show 0 and the NET annunciator should illuminate.

2.Remove the container, box, or item from the scale. The WEIGHT display should show a negative weight value (weight of the tared container, box, or item).

3.Press TARE to reset tare to zero.

Digital Tare, Tare Weight Known

1.If the tare weight value is known, use the numeric keypad to key in the value and then press TARE.

2.Press TARE to reset tare to zero.

NOTE: For digital tare entry, the decimal must be in the appropriate place as it would be displayed in the WEIGHT display. For example, .250 would be entered as 0.250, not .250. The WEIGHT display shows weight entered with a negative sign indicating that it is a tare weight.