Siemens SITRANS P DS III - Safety-Related Characteristics

Functional safety
8.4 Safety-related characteristics
SITRANS P DS III with PROFIBUS PA
Operating Instructions, 06/2013, A5E00053276-07
133
● Simulate various measured values and statuses.
● Verify that the measuring tolerance is within the range of the application-specific
measuring error for the safety function.
– Check the zero point, e.g. in a pressure-less state, for gauge and differential pressure.
– You check the zero point, e.g. with a defined pressure, for absolute pressure.
Enabling write protection
After parameterizing/commissioning:
1. Enable write protection by entering the PIN in SIMATIC PDM. See Activate write
protection using PIN in SIMATIC PDM (Page 145).
Operation via buttons and PROFIBUS communication is blocked.
2. Protect the keys from unintended change in the parameters, e.g. by lead-sealing.
See also
Warning and alarm limits (Page 117)
8.4
Safety-related characteristics
The safety characteristics necessary for using the system are listed in the "SIL Declaration of
Conformity". These values apply under the following conditions:
● SITRANS P DS III pressure transmitters are only used in applications with a low demand
rate for the safety function (low demand mode).
● The safety-relevant parameters/settings were entered before the safety-instrumented
operation via PROFIBUS communication. Check the safety-relevant parameters/settings
by means of PDM; refer to chapter "Settings (Page 132)".
● The safety function test has been concluded successfully.
● The transmitters are protected from accidental and unauthorized changes/operation.
● Fault rates are calculated on the basis of a mean time to repair (MTTR) of eight hours
(order option C21).
● Only one SITRANS P DS III device is required for single-channel operation in accordance
with SIL 2.
● Secure data transmission is only guaranteed when using a PROFIsafe master.