
1.2RTD Input to Digital Conversion
Engineering Units The following equations may be used to calculate the digital word in decimal format which will result from a particular RTD input:
RTD Mode, Digital Word (WX) = Degrees X 10
Millivolt Mode, Digital Word (WX) = Millivolts X 100
As an example, the following figure illustrates the effects of a change in input level going from 0 degrees to 102.4 degrees in the RTD Input Mode.
| Figure |
Scale Units | When data format is selected as SCALE the full temperature range of the |
| RTD is scaled as an unsigned integer from 0±32000. The following formula |
| may be used to calculate the scaled integer value: |
| Scaled Integer = (measured temp ± min temp) ⎟(max temp ± min temp) ⋅ |
| 32000 |
| For example the scaled integer offset at 0_C for a 100 Pt RTD is: |
| Scaled Integer = 0 ± (±199.8) ⎟(849 ± (±199.8)) ⋅ 32000 = 6091 |
Description | SIMATIC 505±2557 Installation and Operation Guide |