Siemens SIWAREX MS, Device Manual

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Weighing
Functions
Decimal place for remote
display and ASCII weight
output BYTE 1 2 0...5
For description see chapter
5.2.13
Maximum negative
weight for zero setting BYTE 1 1 Negative range of zero setting device [in % of WB
BB
]
For description see chapter
5.2.14
Maximum positive weight
for zero setting BYTE 1 3 Positive range of zero setting device [in % of WB
BB
]
For description see chapter
5.2.15
Tare max. weight T- BYTE 1 100 Subtractive tare device range
in % of weighing range
For description see chapter
5.2.16
TTY protocol selection WORD 2 0 0: Protocol for S102 by Siebert
1: ASCII Protocol
Other definitions not permitted.
For description see chapter
5.2.17
Reserved STRING[4] 6 “----” “----”:
For description see chapter
5.2.18
Unit STRING[4] 6 “kg” Weight unit for weight display
For description see chapter
5.2.19
56
Table 5-1 Allocation of DS3
5.2.1 DS3 – Adjustment Digits 0, 1, 2, for Zero Point and Adjustment Weights 1, 2
The analogue measurement value coming from the load cells is converted into a
digital value with an analog-digital converter. A weight value is then calculated from
this digital value. All functions of the SIWAREX MS then use this weight value to
determine the status and for messages.
To calculate the weight value from the digital value, the characteristic curve of the
measurement system must be determined. In the simplest case, the characteristic
curve is defined by points 0 and 1. The first operating point (point 0) is always
determined by the empty scale alone with its own construction weight. The weight
of the scale’s own construction causes the load cell to supply a measurement
voltage to SIWAREX MS. After analog-digital conversion of the measurement
voltage, the digital value (adjustment digits for zero point) is assigned the zero
point (Weight = 0).
If the scale is loaded with a known adjustment weight (e.g. 100 % of the
measurement range), then the second operating point can be determined. The new
digital value from the analog-digital converter is now assigned the adjustment
weight.
In addition, the characteristic curve can be linearized using a further point lying
above point 1.
Ensure that the difference between two adjustment weights is at least 5 % of the
total nominal load of all load cells. This will ensure that the adjustment points are
not too close together.
The adjustment consists of the following steps:
Define adjustment weights and other parameters of the DS 3 data record.
Send DS 3 to the scale
With an empty scale, give the command “Valid adjustment weight = 0”
SIWAREX MS 5-21