SBC PCD1 Series - Page 200

Saia-Burgess Controls AG
Manual Manual PCD 1 / PCD 2 Series │ Document 26 / 737 EN22 │ 2013-11-26
5
Input/output (I/O) modules
5-64
Analogue input modules
Temperature measurement with Pt 1000
In the temperature range – 50 °C to + 200 °C, the following formulae can be used for
working to an accuracy of ± 1 % (± 1.5 °C). Repeating accuracy is signicantly higher.
T=temperature in ° C DV=digital value (0 … 1023)
Example 1: digital value DV=562
temperature T in ° C ?
DV=digital value (0 … 1023) T=temperature in ° C
Example 2: preset temperature T = –10 °C
corresponding digital value DV ?
Resistance measurement up to 2.5 kΩ
Special temperature sensors or any other resistances up to 2.5 kΩ can be connected
to the PCD2.W220. The digital value can be calculated as follows:
where 0 ≤ DV ≤ 1023 and R=the resistance to be measured in Ω.
DV=
4092 • R
(7500 + R)
T[° C]=
- 261,8
DV
2.08 - (0.509 • 10
-
³ • DV)
T[° C]=
- 261,8
562
2.08 - (0.509 • 10
-
³ • 562)
= 51.5 °C
DV=
2.08 • (261.8 + T)
1 + (0.509 • 10
-
³ • (261.8 + T))
DV=
2.08 • (261.8 - 10)
1 + (0.509 • 10
-
³ • (261.8 - 10))
= 464