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Register Value Converted Decimal Calculated Temperature
(Converted Decimal ÷ 20)
Two's Complement Val-
ue
Decimal Value
0000 0000 0000 0010 2 2 0.10
0000 0000 0000 0001 1 1 0.05
0000 0000 0000 0000 0 0 0
1111 1111 1111 1111 65535 -1 -0.05
1111 1111 1111 1110 65534 -2 -0.10
1111 1111 1111 1101 65533 -3 -0.15
1111 1111 1111 1100 65532 -4 -.20
1111 1111 1111 1011 65531 -5 -0.25
1111 1100 0001 1000 64536 -1000 -50
5.9.1 Mapping Unit Types
Using signed or unsigned value types allows the user to generically map any input to any output. The signed and unsigned
values read the null and span parameters to create the linear translation between one scale and another. The output type
is set to mA or V.
Output = (Fullscale/Span)(InputValue − Null) + Offset
Output Scale Fullscale (range) Offset
0–20 mA 20 mA 0 mA
4–20 mA 16 mA 4 mA
0–10V 10V 0V
Fullscale. Defined in the table; the output range.
Span. The total range of values mapped to the output.
Null. The starting point for the output scale.
Input Value. The value mapped to the output.
Offset. Defined in the table; the starting output value.
Example: Temperature Map
Map a temperature input from a Node to a 4–20 mA output. The starting temperature is −20 °F and the last tempera-
ture will be 50 °F (4 mA = −20 °F, 20 mA = 50 °F). This defines the null as −20 °F and the span as 70.
With an input temperature value of −5 °F, the output value will be:
Output = (Fullscale ÷ Span)(InValue − Null) + Offset
(Fullscale ÷ Span) = 16 ÷ 70 = 0.22857
(Value − Null ) = −5 − (−20) = 15
Offset = 4
Output = 0.22857 × 15 + 4 = 7.42 mA
SureCross DX80 and Performance DX80 Product Manual
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