PD 642 / 643 AnalogIn scaling; Thermocouple temperature
This document applies to the PD 642 as
well as the PD 643, for both modules when used for thermocouple temperature
measurement.
The AnalogIn register shows the
temperature in °C.
PD 642 / 643 (in Thermocouple mode)
Analogue Input modules need to be configured for the type of thermocouple
sensor being used.
This is configured in the ChConfig.SignalType
register.
Thermocouple types (see datasheet):
- Type R. Platinum-13% Rhodium/Platinum
(-50 C – 1768 C)
- Type S. Platinum-10% Rhodium/Platinum
(-50 C – 1768 C)
- Type B. Platinum-30% Rhodium/Platinum
(0 C – 1820 C)
- Type J. Iron/Copper-Nickel (-109.1 C –
1200 C)
- Type T. Copper/Copper-Nickel (-166.5 C
– 400 C)
- Type E. Nickel-Chromium/Copper-Nickel
(-94.8 C – 1000 C)
- Type K.
Nickel-Chromium/Nickel-Aluminium (-153.7 C – 1372 C)
- Type N.
Nickel-Chromium-Silicon/Nickel-Silicon (-270 C – 1300 C)
The thermocouple sensor measures the
temperature difference between two points. One point is the actual
process and the other point is at the junction of the sensor cable and the
installation cable going to the PD 642 / 643 module.
The temperature measured by the PD 642 /
643 is the Process temperature minus the temperature at the point of cable
connection. To automatically remove the influence of the cable junction
temperature, the PD 642 / 643 adds the value of OffsetTemp
register to the measured temperature before presenting the measurement in
AnalogIn.
If the sensor cable / installation cable
junction is situated in a place having a constant temperature, the value of OffsetTemp
can be set as a constant.
If the temperature at the sensor / cable
junction varies, the temperature of the junction has to be measured by an
absolute temperature sensor (e.g. Pt100) and stored in the OffsetTemp
register. This is also known as "cold-junction compensation".
Thermocouple sensors are available with
different cable lengths allowing several thermocouple connections to be made
at the same place and thus share a common reference temperature sensor.
(See also: AnalogIn)
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Type R:
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-50 °C - 1768 °C
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Platinum-13% Rhodium/Platinum
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
1°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
1°C
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Resolution:
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0,5°C
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Repeatability:
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± 1°C
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Type S:
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-50 °C - 1768 °C
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Platinum-10% Rhodium/Platinum
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
1,1°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
1,1°C
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Resolution:
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0,6°C
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Repeatability:
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± 1,2°C
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Type B:
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0 °C - 1820 °C
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Platinum-30% Rhodium/Platinum-6%
Rhodium
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
1,4°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
1,4°C
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Resolution:
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0,77°C
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Repeatability:
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± 1,54°C
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Type J:
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-109,1 °C - 1200 °C
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Iron/Copper-Nickel
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
0,23°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
0,23°C
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Resolution:
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0,1°C
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Repeatability:
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± 0,2°C
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Type T:
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-166,5 °C - 400 °C
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Copper/Copper-Nickel
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
0,37°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
0,37°C
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Resolution:
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0,13°C
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Repeatability:
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±0,26°C
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Type E:
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-94,8 °C - 1000 °C
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Nickel-Chromium/Copper-Nickel
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
0,27°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
0,27°C
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Resolution:
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0,08°C
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Repeatability:
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± 0,16°C
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Type K:
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-153,7 °C - 1372 °C
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Nickel-Chromium/Nickel-Aluminium
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
0,36°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
0,36°C
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Resolution:
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0,15°C
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Repeatability:
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± 0,3°C
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Type N:
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-270 °C - 1300 °C
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Nickel-Chromium-Silicon/Nickel-Silicon
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Measurement error @ 0°C to +50°C:
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max. ± 0,1% of actual temperature ±
0,36°C
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Measurement error @ -25°C to +70°C:
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max. ± 0,3% of actual temperature ±
0,36°C
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Resolution:
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0,18°C
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Repeatability:
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± 0,36°C
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Related Topics
Pt100 / Pt1000 /
Thermocouple Offset adjustment
Notification
Limit alarms
Application Notes for
PD 640 (mA)
Application Notes
for PD 641 / 643 (Pt100 / Pt 1000)
Application Notes
for PD 642 / 643 (mV / thermocouple)
Analogue modules
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