Redundant Antivalent Signal Logic With Discrepancy Analysis - Siemens SIDOOR ATD401W System Manual

SIDOOR functions
3.4 Safety functions
3.4.2.5

Redundant antivalent signal logic with discrepancy analysis

In the case of 1oo2 evaluation, the sensor is routed to two different, mutually antivalent
channels and is therefore evaluated by the controller twice. The discrepancy analysis is
performed between the two channels of the 1oo2 evaluation in the controller. If there is a
discrepancy between the input signals after expiry of the parameterized discrepancy time,
e.g. due to breakage of a sensor cable, the internal signal is set to "0". The discrepancy
analysis at the input channels is performed with the "AND0" discrepancy analysis block (for
more, see also section Free function blocks (Page 76)). This special kind of signal routing
achieves PLd and enables both high availability and error detection.
The following graphics show an example of 2-channel antivalent wiring of a sensor
(antivalent).
Antivalent connection of an antivalent sensor to two channels
A 2-channel sensor is required for the signal (1oo2 evaluation)
Figure 3-12
92
Connect the switchgear to the change-over contact, 2-channel nonequivalent
ATD4xxW Door Controller for Industrial Applications
System Manual, 01/2017, A5E38080677-AB