AXL F UTH4 1H
8672_en_02 PHOENIX CONTACT 11
5.9 Technical data for cold junctions
Internal cold junctions
Simple cold junction compensation can be implemented for
the thermocouple inputs using the internal cold junctions.
To read the temperature of each internal cold junction for TC
channels, parameterize the sensor type as "Cold Junction".
For the accuracy, please refer to the tables of the tolerance
values.
Compensation of the mounting position of the internal
cold junction
In order that maximum accuracy is also achieved when in-
stalled in various different mounting positions, it is possible
to compensate the mounting position of the internal cold
junction.
Parameterize this compensation using the ParaTable ob-
ject, data format, mounting position.
Tolerances of the internal cold junction
* Thermally steady system without external heat influence
1. The data refers to nominal operation (U
A
=24V) in the
preferred mounting position (horizontal).
2. The measurement is performed within an AxiolineF sta-
tion in which another AXLFUTH41H module is located
to the right and left of the module in question.
ExternalPt 100 cold junctions
When using external isothermal blocks or distributed termi-
nal boxes, an external cold junction is recommended. The
advantage of this is an improved switch-on behavior and the
very fast thermal transient period in the event of sudden
changes to the ambient temperature of the measuring sta-
tion.
You can connect up to two Pt 100 sensors to the
AXLFUTH41H module.
You can also use the inputs for the external cold junction
sensors as sensor inputs for any applications with Pt100
and connection with 2-wire technology. To do so, parame-
terize the sensor type as “Cold junction” and the cold junc-
tion type as “External Pt100” on the corresponding connec-
tor.
Tolerances of the external Pt100 cold junction inputs
The data contains the offset error, gain error, and linearity
error in its respective setting.
The data is valid for nominal operation (preferred mounting
position, U
A
=24V).
The documented typical tolerances were determined for ref-
erence cable type LiYCY (TP) 2 x 2 x 0.5mm² with a con-
nection length <1m.
The drift data and the tolerances specified as a percentage
refer to the measuring range final value of+400°C.
The typical data has been determined in an example Axi-
olineF station.
Typical tolerance values are measured application values
that are based on the maximum variance of all test objects.
The maximum tolerance values represent the worst-case
measurement inaccuracy. They contain the theoretical max-
imum possible tolerances in the corresponding measuring
ranges as well as the theoretical maximum possible toler-
ances of the calibration and test equipment. The data is valid
for at least 24months from delivery of the module. Thereaf-
Internal cold junction
Connection method 2-wire connection
Sensor type Pt100 DIN
R
0
(sensor resistance at T
A
=0°C) 100 Ω
Measuring range -55°C...+125°C
Resolution (process data) 0.1 K/LSB
Resolution (floating point object) < 0.001 K
Filter time 120 ms
No. Tolerance struc-
ture
Temper-
ature
Tolerances
Typ. Max.
1 Cold junction tempera-
ture drift
-25°C ...
+60°C
10 ppm/K 25 ppm/K
2 Total tolerance of the in-
ternal cold junction
+25°C ±0.15K ±1.76K
3 Total tolerance of the in-
ternal cold junction
-25°C ...
+60°C
±0.85K±2.4K
ExternalPt 100 cold junctions
Connection method 2-wire connection
Sensor type Pt100 DIN
R
0
(sensor resistance at T
A
=0°C) 100 Ω
Measuring range -100 °C...+400 °C
Resolution (process data) 0.1 K/LSB
Resolution (floating point object) < 0.001 K
Filter time 120 ms
No. Ambient
temperature
Tolerances
Typ. Max.
1Tolerances +25°C ±0.3K±0.8K
2 Drift -25°C ... +60°C ±10ppm/K ±25 ppm/K
