RTD measurement

In principle, the electrical resistance measuring range can be set independently of the RTD transformation. For this reason, achievable temperature measurement accuracies are specified below as a function of the electrical resistance measurement range. When selecting the combination, it is important to ensure that the correct, sufficient electrical resistance range is selected depending on the desired area of application of the sensor, e.g. the 50 Ω range in combination with a PT1000 sensor will rarely be useful. A setting must therefore be selected for

• the electrical resistance measuring range in [Ω] in CoE 0x80n0:01
• the transformation/conversion R → Ω in CoE 0x80n0:14

RTD measuring range

Fig.78: Chart: RTD measuring range

In temperature mode, only the legacy range is available, the extended range is not available.

The temperature display in [°C/digit] (e.g. 0.1°/digit or 0.01°/digit) is independent from the electrical measurement. It is “just” a display setting and results from the PDO setting, see chapter "Comissioning".

Implemented characteristic curves, overview

RTD types and transformations supported by the ELM324x

• None (no transformation)
• PT100 (-200 … 850 °C)
• PT200 (-200 … 850 °C)
• PT500 (-200 … 850 °C)
• PT1000 (-200 … 850 °C)
• NI100 (-60 … 250 °C)
• NI120 (-60 … 320 °C)
• NI1000 (-60 … 250 °C)
• NI1000 TK5000 (-30 … 160 °C)
• KT100/110/130/210/230 KTY10/11/13/16/19 (-50 … 150 °C)
• KTY81/82-110,120,150 (-50 … 150 °C)
• KTY81-121 (-50 … 150 °C)
• KTY81-122 (-50 … 150 °C)
• KTY81-151 (-50 … 150 °C)
• KTY81-152 (-50 … 150 °C)
• KTY81/82-210,220,250 (-50 … 150 °C)
• KTY81-221 (-50 … 150 °C)
• KTY81-222 (-50 … 150 °C)
• KTY81-251 (-50 … 150 °C)
• KTY81-252 (-50 … 150 °C)
• KTY83-110,120,150 (-50 … 175 °C)
• KTY83-121 (-50 … 175 °C)
• KTY83-122 (-50 … 175 °C)
• KTY83-151 (-50 … 175 °C)
• KTY83-152 (-50 … 175 °C)
• KTY84-130,150 (-40 … 300 °C)
• KTY84-151 (-40 … 300 °C)
• KTY21/23-6 (-50 … 150 °C)
• KTY1x-5 (-50 … 150 °C)
• KTY1x-7 (-50 … 150 °C)
• KTY21/23-5 (-50 … 150 °C)
• KTY21/23-7 (-50 … 150 °C)
• B parameter
• DIN IEC 60751
• Steinhart-Hart

The following transformations are implemented, but can only map a partial temperature range due to the electrical measuring range being limited to 5 kΩ:

• NTC 1k8 (R0 = 4940 ohm, 0 … 130 °C)
• NTC 1k8 (R0 = 5200 ohm, 1 … 150 °C)
• NTC 2k2 (R0 = 7373 ohm, 8 … 130 °C)
• NTC 3k (R0 = 9822 ohm, 14 … 80 °C)
• NTC 5k (R0 = 16325 ohm, 25 … 100 °C)
• NTC 10k (R0 = 27280 ohm, 45 … 110 °C)
• NTC 10k (R0 = 29490 ohm, 45 … 150 °C)
• NTC 10k (R0 = 29588 ohm, 45 … 130 °C)
• NTC 10k (R0 = 32639 ohm, 45 … 130 °C)
• NTC 10k (R0 = 32650 ohm, 45 … 150 °C)
• NTC 10k (R0 = 32660 ohm, 45 … 130 °C)
• NTC 10k (R0 = 32770 ohm, 42 … 130 °C)
• NTC 20k (R0 = 70200 ohm, 58 … 150 °C)
• NTC 100k (R0 = 326600 ohm, 112 … 130 °C)
• NTC 100k (R0 = 327240 ohm, 112 … 270 °C)

The Pt types are implemented in accordance with DIN EN 60751/IEC751 with

• A = 0.0039083 °C^-1
• B = -5.775 * 10^-7 °C^-2
• C = -4.183 * 10^-12 °C^-3

and thus α = 0.003851 °C^-1. If other coefficients are required, these must be entered directly in the CoE via the "DIN IEC 60751" setting; if only α is used for the calculation, the CoE scaler 0x80n0:2E "linear" must be used.