Siemens simatic s5 Handbuch Seite 5

Warning
Risks involved in the use of so-called SIMATIC-compatible modules of
non-Siemens manufacture
"The manufacturer of a product (SIMATIC in this case) is under the general
obligation to give warning of possible risks attached to his product. This obligation
has been extended in recent court rulings to include parts supplied by other
vendors. Accordingly, the manufacturer is obliged to observe and recognize such
hazards as may arise when a product is combined with products of other
manufacture.
For this reason, we feel obliged to warn out customers who use SlMATlC
products not to install so-called SIMATIC-compatible modules of other
manufacture in the form of replacement or add-on modules in SlMATlC
systems.
Our products undergo a strict quality assurance procedure. We have no knowledge
as to whether outside manufacturers of so-called SIMATIC-compatible modules
have any quality assurance at all or one that is nearly equivalent to ours. These so-
called SIMATIC- compatible modules are not marketed in agreement with Siemens;
we have never recommended the use of so-called SIMATIC-compatible modules of
other manufacture. The advertising of these other manufacturers for so-called
SIMATIC-compatible modules wrongly creates the impression that the subject
advertised in periodicals, catalogues or at exhibitions had been agreed with us.
Where so-called SIMATIC-compatible modules of non-Siemens manufacture are
combined with our SlMATlC automation systems, we have a case of our product
being used contrary to recommendations. Because of the variety of applications of
our SlMATlC automation systems and the large number of these products marketed
worldwide, we cannot give a concrete description specifically analyzing the hazards
created by these so-called SIMATIC-compatible modules.