Siemens SIMATIC Operating Instructions Manual page 121

Special Features for Fault Detection in Use Case 2.2
The following table presents fault detection according to the sensor supply and the
parameter assignment for the short-circuit test:
Table 8-24
Short circuit of DI 0 with DI 1
Short circuit of DI 0 with DI 2
Short circuit of DI 0 with DI 3
P-short circuit of DI 0
M-short circuit of DI 0
Discrepancy error
P-short circuit of sensor
supply
M-short-circuit in sensor
supply or defective
Short-circuit in sensor supply
at DI 0
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.
If the short-circuit test is not enabled or the sensor supply to digital inputs is set to
"external", the wiring between the sensor and the input channel must be short circuit-proof.
ET 200pro Distributed I/O System - Fail-Safe Modules
Operating Instructions, 05/2007, A5E00394073-02
F-Switch PROFIsafe Electronic Module: Fault Detection
Example of Fault
WARNING
8.3 F -Switch PROFIsafe Digital Electronic Module
Fault detection in case of ...
Internal sensor supply Internal sensor supply
and short-circuit test
enabled
Yes*
No
Yes*
Yes*
Yes*
Yes
Yes
Yes
Yes*
Yes
Fail-Safe Electronic Modules
and short-circuit test
disabled
Yes*
No
Yes*
Yes*
Yes*
Yes
No
Yes
Yes*
Yes
External sensor
supply
Yes*
No
Yes*
Yes*
Yes*
Yes
No
Yes
Yes*
Yes
121