Siemens SIMATIC Operating Instructions Manual page 80

Fail-Safe Electronic Modules
8.1 8 /16 F-DI DC24V PROFIsafe Digital Electronic Module
In order to achieve SIL3/Category 4 with this wiring, you must install a suitably qualified
sensor, for example, in accordance with IEC 60947.
Assignable Parameters for Use Case 3.2
Set the "Evaluation of the sensors" parameter to "1oo2 evaluation" and the "Type of sensor
interconnection" parameter to "2-channel nonequivalent" for the relevant input. Enable the
"Short-circuit test" parameter.
Specific Characteristics for Fault Detection (Use Cases 3.1 and 3.2)
The following table presents fault detection according to the sensor supply and the
parameter assignment for the short-circuit test:
Table 8-13
Short circuit of DI 0 with DI 1
Short circuit of DI 0 with DI 4
Short circuit of DI 0 with DI 5
P-short circuit of DI 0
M-short circuit of DI 0
Discrepancy error
P-short circuit of Vs1
M-short circuit of Vs1, or Vs2 defective
Short circuit of Vs1 with Vs2
Fault in read/test circuit
Supply voltage fault
*: Fault is detected only in case of signal corruption. That is, the signal read differs from the sensor
signal (discrepancy error). If there is no signal corruption relative to the sensor signal, fault detection
is not possible and is not required from a safety standpoint.
80
WARNING
F-DI Modules: Fault Detection (Use Cases 3.1 and 3.2)
Example of fault Fault detection with internal sensor supply and enabled
short-circuit test for ...
Sensor 2-channel equivalent
Yes*
Yes*
Yes*
Yes
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
ET 200pro Distributed I/O System - Fail-Safe Modules
Operating Instructions, 05/2007, A5E00394073-02
Sensor 2-channel
nonequivalent
Yes*
Yes
Yes*
Yes
Yes*
Yes
Yes
Yes
Yes
Yes
Yes