PS081 datasheet(51/155 Pages) AMSCO

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PSØ81

PS081 can correct uncompensated load cells (cells without a gain compensation resistor Rspan),

too. It therefore uses the temperature measurement information instead of the Rspan value. This

mode is activated by setting rspan_by_temp = 1 in register 1. Again, the adjustments are done by

means of factors Mult_TKO and Mult_TKG. The accuracy of this compensation depends mainly on the

accuracy and Tk of the resistors used for the temperature measurement. Improvements by a fac-

tor 6 to 8 compared to the uncompensated load cell can be achieved. This is normally sufficient for

making a simple temperature correction for commercial scales. For high-end scales or legal for trade

scales we recommend to use an ordinary Rspan in combination with the here described Mult_TkG

and Mult_TkO method.

In application note AN021 we describe the method of the temperature compensation by the means

of 2 resistors (Rspan_by_temp) and the scope of its use in detail.

3.6.3

Annotations Rspan

PICOSTRAIN needs only one Rspan resistor. As the common mode rejection ratio (CMRR) of the

PICOSTRAIN products is nearly infinite (up to 135dB) there is no need to use two Rspan resistors.

Indeed, PICOSTRAIN can not handle bridges with two Rspan resistors.

The easiest is to use load cells which natively have only 1 Rspan resistor. Nevertheless, if you want

to make a first tests with a load cell which has 2 Rspan you simply can shortcut one of them in the

following manner:

Figur 3.27 Shortcut Rspan

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PS081 Datasheet(PDF) 51 Page - ams AG