HB-37420-810-01-25F-EN SMX100 Installation manual.docx Page 77 of 260
Version: 25F
4.2.1.2 DC digital sensors/inputs
The SMX100 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:
SMX 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
I05 – I08. Falling below the defined threshold value a module triggers a module alarm.
Diagnostics functions to be activated by parameterization:
Cross-shorting test:
The SMX 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 SMX-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 SMX 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.
Same test as before, but additional monitoring of the input signals for compliance with the
defined level connections within a time window of 0.5 seconds. Defining the levels over a time
period of > 0.5 seconds triggers a module alarm.
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