Siemens SITRANS TR200 Produktinformation Seite 12

General safety notes
Safety-instrumented system
This chapter describes the functional safety in general and not specific to a device. The devices in the examples are
selected as representative examples. The device-specific information follows in the next chapter.
Description
The sensor, logic unit/control system and final controlling element combine to form a safety-instrumented system, which
executes a safety function.
S Failure signal
F
Figure 1 Example of a safety-instrumented system
Functioning of the system as shown in the example
The transmitter generates a process-specific analog signal. The downstream control system monitors this signal to ensure
that it does not fall below or exceed a set limit value. In case of a fault, the control system generates a failure signal of < 3.6
mA or > 22 mA for the connected positioner, which switches the associated valve to the specified safety position.
Functional safety for SITRANS TR200/TR300
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A5E03263689-02, 08/2010