Справочник Пользователя для Siemens 505-2557
Description
1-4
SIMATIC 505–2557 Installation and Operation Guide
1.2
RTD Input to Digital Conversion
The following equations may be used to calculate the digital word in decimal
format which will result from a particular RTD input:
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
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.
input level going from 0 degrees to 102.4 degrees in the RTD Input Mode.
Figure 1-2
Example Change Input Level
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:
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
Engineering Units
Scale Units