Siemens S7-300 Installation And Operating Manual page 267

Degree of severity 3 and higher


Protection of shielded signal lines (inputs) from surge stress according to IEC 61000-4-5
Up to degree of severity 3

To achieve failure criterion A according to IEC 61000-4-5..., the repetition factor for HART
communication must be set at a value greater than 0.
* In redundant operation, the module with the higher start address is automatically the secondary
master.
Note
The maximum cable lengths currently specified in this manual ensure against functional
impairment, even without more precise examination of the boundary conditions. If the
boundary conditions, such as EMC, cable type, cable routing, etc. are examined more
closely, longer cables can be used for all F-SMs.
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
Symmetrical (L+ to M)
Asymmetrical (L+ to PE, M to PE)
Asymmetrical (shield to PE)
9.3 SM 336; F-AI 6 x 0/4 ... 20 mA HART
Technical data
External protective elements required
± 1 kV; 1.2/50 μs
± 2 kV; 1.2/50 μs
No external protective elements required
± 2 kV; 1.2/50 μs
Analog modules
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