Siemens SIPART DR21 User Manual

2 Technical Description
2.5 Function principle
Manual
30
SIPART DR21
C73000-B7476-C143-08
6DR2805-8J Measuring range plug
D Measuring range plug for current 0/4 to 20 mA or voltage 0/2 to 10 V
The measuring range plug is used in connection with the UNI-module to measure current- or
voltage. The input variable is reduced to a signal range of 0/20 to 100 mV by a voltage di-
vider or shunt resistors in the measuring range plug.
Wiper resistors with 250 Ω or 50 Ω are available optionally at 2 different terminals for 0/4 to
20 mA-signals.
The electrical isolation of the UNI-module is retained even when the measuring range plug is
used.
6DR2801-8D 2 DO relays
D Digital output module with 2 relay contacts
To convert 2 digital outputs to relay contacts up to 35 V UC.
This module is equipped with 2 relays whose switching contacts have potential free outputs.
The RC-combinations of the spark quenching elements are respectively parallel to the rest-
and working contacts.
In AC-consumers with low power the current flowing through the capacitor of the spark
quenching element when the contact is open may interfere (e.g. the hold current of some
switching elements is not exceeded). In this case the capacitors (1 μF) must be removed
and replaced with low capacitance capacitors.
The 68 V suppressor diodes parallel to the capacitors act additionally to reduce the induced
voltage.
CAUTION
The relays used on the digital output module are designed for a maximum
rating up to UC 35 V. The same applies for the air- and creep lines on the
circuit board. Higher voltages may therefore only be switched through appro-
priately approved series connected circuit elements under observance of the
technical data and the pertinent safety regulations.
6DR2801-8E 2 DI and 4 DO
D Digital signal module with two digital inputs and 4 digital outputs
The module serves to extend the digital inputs and digital outputs already existing in the
standard controller.
The inputs are designed in 24-V-logic and are potential-bound. The functions are assigned to
the inputs- and outputs by configuration of the controller. (Structure switches S23 to S33,
S58toS68).
The digital outputs are short-circuit-proof and can drive commercially available relays or the
interface relays 6DR2804-8A/8B directly.

Siemens SIPART DR21 Specifications

General

Brand	Siemens
Model	SIPART DR21
Category	Controller
Language	English