Analog modules
9.3 SM 336; F-AI 6 x 0/4 ... 20 mA HART
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
241
Load voltage for the module in 4-wire transducer, high-availability application
U
LoadModule
= U
Ri
+ U
Line
+ U
Z_6V2
WARNING
The fail-safe performance characteristics of the external components (e.g., transducer,
diodes, Zener diodes) are not included in the fail-safe performance characteristics of the
module (see technical data of the module). These must be determined and/or taken into
account in a safety examination.
WARNING
You must take the following into consideration when selecting Zener diodes for high-
availability interconnection of the analog module:
Taking into account the tolerances, the wire break voltage must be greater than the
maximum voltage drop on the input resistance of the module. In particular, the residual
current must be considered since it affects the measurement result.
For safety reasons, we recommend the use of a variety (diversity) of Zener diodes
(common cause error).
For example, you could use the following Zener diodes: 5.6 V (1N4734A) and 6.2 V
(1N4735A), or use MTA 6ES7650-1AH51-5XX0 with 6ES7650-1BB51-0XX0 and 6ES7650-
1BC51-0XX0 (see Manual " Marshalled Termination Assemblies ET 200M Remote I/O
Modules (
9.3.5
Applications 1 and 2
Applications 1 and 2
Applications 1 and 2 are omitted because the module supports only safety mode.
9.3.6
Application 3: Safety mode SIL3/Cat.3/PLe
Introduction
Below are the wiring scheme and the parameter assignment of SM 336; F-AI 6 x 0/4 ...
20 mA HART for
●
Application 3: Safety mode SIL3/Cat.3/PLe for "1oo1 evaluation.
Diagnostic messages, possible causes of the problem and their corrective measures are
found in tables
Diagnostic messages of SM 336; F-AI 6 x 0/4 ... 20 mA HART and Diagnostic
messages and associated corrective measures for SM 336; F-AI 6 x 0/4 ... 20 mA HART in
chapter "Diagnostic messages of SM 336; F-AI 6 x 0/4 ... 20 mA HART (Page 257)".