PS081 datasheet(49/155 Pages) AMSCO

49 / 155 page

acam-messelectronic gmbh - Friedrich-List-Str.4 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de

3-26

PSØ81

A simple example program to display the results could be:

ramadr

; HB0 result

move

x , r

; Load x-Accu with the result

move

y , 2

; Load y-Accu with the comma position

no2lcd

x , 2

; Convert into 7-segment display

newlcd

; Indicate new value to the LCD-driver

clrwdt

; setback the watchdog

stop

; Hold the µC

3.6.1

Off-center Correction for Quattro Scales

Several scales like body scales have four load cells, each with a half-bridge sensor on it. The indicated

weight might vary with the position on the platform in case the load cells do not all have exactly the

same sensitivity. PSØ81 allows to correct the gain of the half bridges just by software without trim-

ming or adding an additional trim circuit. Each half bridge result is assigned its own multiplication fac-

tor (MULT_HB1 to MULT_HB4). By simply four measurements it is possible to calculate the multipli-

cation factors for the correction. Therefore a nominal load has to be put on each corner of the scale.

Please contact acam for the algorithm to calculate the factors MULT_HB1 to MULT_HB4.

3.6.2

Compensation of Load Cell Gain & Offset Drift (Mult_TKG, Mult_TkO)

Todays high end converters have a very good zero drift and gain drift bevavior. It is about 5 to 10

times better than for a good load cell itself. The real goal is an optimized complete system (scale)

and not only a very good electronic. Therefore, with the PICOSTRAIN family acam has indroduced

a method which is also able to correct the zero drift and the gain drift of the load cell by software

without touching the load cell. This method works only if the load cell has just one compensation

resistor (Rspan)1.

PS081 can measure this resistor and correct it by an algorithm in the µP, based on factors

Mult_TkG for the gain drift and Mult_TKO for the zero drift. This can be done after the production of

the load cell is completed. It is no longer necessary to have a precise compensation resistor on the

load cell. It is not necessary to trim Rspan manually.

A further consequence of this possibility is that it is no longer necessary to trim the load cell exactly

to zero, no zero offset compensation resistors are needed.

see also 3.6.4 Nonlinearity of gain drift over temperature. It may be necessary to add a resistor in

parallel to Rspan to reduce nonlinearity.

Member of the ams Group

PS081 Folha de dados(PDF) 49 Page - ams AG

PS081 Folha de dados(HTML) 49 Page - ams AG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Folha de dados Download

Ligação URL