2 Technical Description
2.5 Function principle
Manual
SIPART DR21
C73000-B7476-C143-08
29
This fine adjustment can be made on the displays on the front module (if structured appropri-
ately). For adjustment with a remote measuring instrument, the analog output can be
assigned to the appropriate input.
The external wiring must be changed for resistance transmitters which cannot withstand the
5 mA wiper current or which have a rated resistance >1 kΩ. The constant current is then not
fed through the wiper but through the whole resistance network of the potentiometer. A volt-
age divider measurement is now made through the wiper. Coarse adjustment is made by a
remote parallel resistor to the resistance potentiometer .
This module can also be used as a current input with adjustable range start and full scale.
The load is 49.9 Ω and is referenced to ground.
6DR2800-8V UNI-module
D Direct connection of thermocouple- or Pt100-sensors, resistance- or mV -transmitters
Measured value sensors such as thermocouples (TC), resistance thermometers Pt100
(RTD), resistance potentiometers (R) or voltage transmitters in the mV -range can be con-
nected directly. The measuring variable is selected by configuring the controller in the
StrS-level (structure switches S6, S8, S9 and S10), the measuring range and the other para-
meters are set in the CAE3-menu. The sensor-specific characteristics (linearization) for ther-
mocouples and Pt100-resistance thermometers are stored in the contoller’s program mem-
ory and are automatically taken into account. No settings need to be made on the module
itself.
The signal lines are connected by a plug terminal block with screw-type terminals. When
using thermocouples with internal reference point, this terminal block must be replaced by
the terminal 6DR2805-8A. With the measuring range plug 6DR2805-8J in place of the ter-
minal block, the measuring range of the direct input (0/20 to 100 mV) can be extended to 0/2
up to 10 V or 0/4 up to 20 mA.
The UNI-module operates with an AD-converter with 18 bit resolution. The measuring inputs
and ground of the standard controller are electrically isolated with a permissible common
mode voltage of 50 V UC.
The UNI-module can only be used at slot 1 (AI3).
6DR2805-8A Reference point
D Terminal with internal reference point for thermocouples
This terminal is used in connection with the UNI-module for temperature measuring with
thermocouples at an internal reference point. It consists of a temperature sensor which is
pre-assembled on a terminal block and plated to avoid mechanical damage.
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