UK
Field modules DP
29
8.3.3 AC2634 FieldModuleDP 4AI (PT100) M12
The analogue module AC2634 allows direct connection of resistance sensors� The
circuit can operate sensors in 2, 3 or 4-wire technology�
Linear performance over the entire temperature range is accomplished via a
micro-processor� The temperature range is freely selectable�
The module can also be used for resistance measurement� In this case, the
measuring value is output in a range from 10 Ω to 1.2/5.0 kΩ with a resolution of
1/16 Ω (The internal resolution of the resistance value is 1/255 Ω).
In the temperature range of the Pt100 sensor in 4-wire technology, the resolution is
0�1 °C� Sensor malfunction, e�g� wire break, is indicated via error LEDs�
The module is equipped with various features� The default settings have been
selected in such a way that device configuration is usually not necessary�
The module is parameterised via the fieldbus�
Supply voltage
U
B
powers the fieldbus and the sensor electronics� It is electrically isolated from U
L
�
For module function U
L
is not needed� An infeed is not necessary�
Connections
4-wire technology
4-wire technology allows measurement and correction of measuring errors which
are caused by the ohmic resistance of cables and contacts�
3-wire technology
The resistance is only measured in one direction to the resistance sensor and then
multiplied by two� The ingoing and outgoing lines must have an almost identical
ohmic resistance�
Two-wire technology
Measuring errors might occur which vary greatly depending on temperature deltas
and conductor cross-sections�
The settings of one channel always affect the entire module and thus all other channels�
All channels should be adjusted identically in order to prevent operating problems�
Pin 5 (shield) is capacitively coupled to the conductive base surface of the module�
