Allen-Bradley MicroLogix 1200 User Manual page 45

Figure 3.1 Linear Relationship Between Temperature and Proportional Counts
The value +32767 corresponds to the highest value for the device. For
example, if a 100Ω platinum 385 RTD is selected, the lowest
temperature of -200° C corresponds to -32768 counts. The highest
temperature of 850° C corresponds to +32767 counts. See Determining
Effective Resolution and Range on page 3-20.
Scaling Examples
Scaled-for-PID to Engineering Units x1
EXAMPLE
• input type = 200Ω Platinum RTD
• α = 0.00385°C
• range = -200 to +850°C
• channel data = 3421(scaled-for-PID)
Engineering Units Equivalent = S
Engineering Units Equivalent = -200°C + [(+850°C -(-200°C)) x (3421/16383)] =
19.25°C
Module Data, Status, and Channel Configuration
Counts
+ 32,767
±200 ˚C
850 ˚C
-32,768
S = -200°C S
LOW HIGH
+ (S - S ) x (channel data/16383)]
LOW HIGH LOW
Publication 1762-UM003A-EN-P - February 2003
3-11
°C
= +850°C