Siemens SIMATIC ET 200S Installation And Operating Manual page 121

Special Features of Fault Detection (Use Case 2.1)
The following table presents fault detection according to the sensor supply and the
parameter assignment for the short-circuit test:
Table 7-22
Short circuit in DI 0 with DI 1
Short circuit in DI 0 with DI 5
P-short circuit in DI 0
M-short circuit in DI 0
Discrepancy error
P-short current in sensor
supply 1
M-short circuit in sensor
supply 1, or sensor supply 2
defective
Short circuit in sensor supply
1 with sensor supply 2
Fault in read/test circuit
Supply voltage fault
*: Fault is detected only in case of signal corruption. In other words, the signal read differs from the
sensor signal (discrepancy error). If there is no signal corruption with respect to the sensor signal,
fault detection is not possible and is not required from a safety standpoint.
Warning
If the short-circuit test is disabled or cannot be enabled, you must install the wire between
the sensor and input channel in a short-circuit-proof manner.
ET 200S Distributed I/O System - Fail-Safe Modules
Hardware Installation and Operating Manual, 07/2005, A5E00103686-04
EM 4/8 F-DI DC24V PROFIsafe: Fault Detection (Application 2.1)
Example of fault
7.5 4/8 F-DI VDC24V PROFIsafe Digital Electronic Module
Fault detection when ...
Internal sensor power
supply and activated
short-circuit test
No
No
Yes
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
Internal Sensor
Supply and
Deactivated Short-
Circuit Test
No
No
No
Yes*
Yes
No
Yes
No
Yes
Yes
Fail-Safe Modules
External Sensor
Supply
No
No
No
No
Yes
No
Yes
No
Yes
Yes
7-61