Manual

(Converted Decimal ÷ 20)

Two's Complement Value Decimal Value

0000 0000 0000 0101 5 5 0.25

0000 0000 0000 0100 4 4 0.20

0000 0000 0000 0011 3 3 0.15

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 to 20 mA 20 mA 0 mA

4 to 20 mA 16 mA 4 mA

0 to 10 V 10 V 0 V

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 to 20 mA output. The starting temperature is −20 °F and the last

temperature 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

Example: Distance Map

Map a distance input from a Node to a 0 to 10 V output. The starting distance is 200 mm and the last distance will be 2000

mm (4 mA = 200 mm and 20 mA = 2000 mm). This defines the null as 200 and the span as 1800.

SureCross Wireless I/O Networks