Rockwell Automation 937CU-AITXF-DC1 Transmitter Supply Converter Installation Instructions - Manual (Page 18)

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Bul. 937C Transmitter Supply Converter Installation Instructions
Editing device data: Input
Example 1: selected unit °C, 0 °C ... 200 °C is to correspond to 4 mA ... 20 mA
•
y = m x + n
• Conversion factor = rise in the graph
m = (y2 – y1) / (x2 – x1)
m = (200 – 0) / (20 – 4) = 12.5
• Zero point = intersection point with the x-axis on the graph, providing that the physical measuring
range starts from 0 (y = 0 °C). The zero point corresponds to the lower measuring range limit (x = 4
mA) from which the measuring range starts.
The zero point can be calculated as follows: n =
y – m x
n = 200 – 12.5 x 20 = -50
y = m x + n
x = (y – n) / m
x = (0 + 50) / 12.5 = 4
2 1 9 8 7 6 5 4 3 10 -1
50
100
150
200
-200
-150
-100
-50
-4 -3 -2 11 12 13 14 15 16 17 18 19 20 x [mA]
y [°C]
Linearization