Installation manual
Page 27 of204
Single channel input element and dual channel processing with low to medium DC by signal processing in two
channels and diagnose by means of cyclic testing, PI / SIL depending on permissible fault exclusions
and test rate for input element.
4.2.1.2 DC digital sensors/inputs
The PSCBR modules ensure far reaching diagnostics functions for the input element. These
are carried out permanently, or optionally (cross-shorting monitoring by means of pulse
identifier, cross-comparison, 2- or multi-channel sensor with/without time-out, start-up test).
Permanently active diagnostics functions:
Cross-comparison:
PSCBR module inputs are in general internally designed with two channels. The status
of input signals is permanently compared crosswise. Only with High signals in both partial
input systems the input is considered a High input, should the signal level deviate between
both channels, the input is set to Low state.
Dynamic test of the partial input system switching threshold:
The switching thresholds for detecting the High level are tested cyclically with a high cycle
rate. Falling below the defined threshold value a module triggers a module alarm.
Dynamic test of the input system's switchability:
The switchability of the input system to Low level is tested for all inputs with a high rate, except
DI5 -- DI8. Falling below the defined threshold value a module triggers a module alarm.
Diagnostics functions to be activated by parameterization:
Cross-shorting test:
The PSCBR modules have pulse signal outputs, identified by an unabiguous signature. When
performing the cross-shorting test the switching elements of the digital sensors / input
elements are supplied with auxiliary voltage by the PSCBR-module via the pulse signal
outputs. The signature is thus stamped on the High signal level of the sensors / input elements
and checked by the PSCBR module. With the signature test short-circuits and cross-shorting
to High signals can be recognized. With alternating use of the pulse signals of multi-contacts,
parallel signal lines or adjacent terminal assignment, cross-shorting between the respective
input elements is detected.
Sensors / input elements with 2- or multi-pole contacts without time-out.
Several contacts can be assigned to the sensors / input elements. These are therefore
compatible with at least 2-channel elements. A High level of the sensor/input element requires
a logic series connection of both contacts.
Example 1:
Input element with 2 normally closed contacts: High level when both contacts are closed.
Example 2:
Input element with 1 normally closed and 1 normally open contact: High level when normally
open contact is actuated and normally closed contact is not actuated.
Sensors / input elements with 2- or multi-pole contacts with time-out.
Summary of Contents for PSCBR-C-10 Series
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