RYM
ASKON
®
200-Modbus
Modbus Slave
User Manual
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Page 49 of 55
3.4.7
Value Scaling and Stepwidth
The following Table 38 gives an overview of how Modbus register datapoints (display values, set points, min.,
max. and offset values) need to be scaled to achieve the desired result at the display. It also shows which stepwidth
is defined for set points.
Physical Value
Unit
Modbus Scaling
A*10^B*(raw + C)
Set Point Stepwidth
Example
A
B
C
raw value
displayed value
No Unit
-
1
0
0
1
100
100
.
0
Temperature
(K)
1
-1
-2740
0,5
2975
0
23.
5
°C
°C
1
-1
0
0,5
235
0
23.
5
°C
°F
1
-1
0
1,0
743
0
74
.
0
°F
°F dec.
1
-1
0
0,5
743
0
74.
5
°F
Flow
m³/h
1
0
0
1
150
150
.
0
m³/h
l/s
1
-1
0
0,1
417
0
41.
7
l/s
cfm
1
0
0
1
88
0
88
.
0
cfm
Pressure
Pa
1
0
0
1
200
200
.
0
Pa
inWC
1
-3
0
0,01
803
0.80
3
inWC
Voltage
V
1
-1
0
0,1
240
0
24.
0
V
Percentage
%
5
-3
0
1
9000
0
45.
0
%
Humidity
%RH
5
-3
0
1
9000
0
45.
0
%RH
Amount CO
2
ppm
1
0
0
1
550
550
.
0
ppm
Note that though a display value or a set point would accept values from 0 to 65535 if unsigned or -32768
to 32767 if signed the value that is displayed is limited to a range from -999 to 9999 because of the 4 digit
display.
!!!
When a fixed-point number reaches a certain limit where an overflow occurs the decimal point is
shifted rightwards (e.g. 999.9 → 1000).
!!!
Whole number values are preferably displayed with the bigger digits. If an overflow occurs the number
is shifted rightwards (e.g. 999 → 1000).
Table 38: Value Scaling and Stepwidth
