Siemens SIMATIC ET 200S Installation And Operating Manual page 133

Special Features of Fault Detection (Use Case 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 7-25
Short circuit in DI 0 with DI 1
Short circuit in DI 0 with DI 4
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.
Requirements for Machine Protection Applications with Category 4
The following requirements apply for applications in machine protection with category 4:
• The wiring between sensors and automation system and between automation system
• that all short circuits listed in the above table are covered. It is sufficient to locate a short
Procedures for locating all short circuits are therefore permissible if single short circuits are
not located,
• cause corruption of read signals compared to the sensor signals or
• cause corruption of read signals compared to sensor signals in the direction that ensures
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 (use cases 3.1 and 3.2)
Example of fault
and actuators must be designed to the state-of-the-art engineering and standards to
prevent short circuit and
circuit, because two faults are required for it to occur (both signal lines in short circuit
have an insulation fault). A multiple short circuit analysis is not required.
safety.
7.5 4/8 F-DI VDC24V PROFIsafe Digital Electronic Module
Fault detection with internal sensor power supply and
activated short-circuit test for...
Sensor 2-channel equivalent
Yes*
Yes*
Yes*
Yes
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
Fail-Safe Modules
Sensor 2-channel non-
equivalent
Yes*
Yes
Yes*
Yes
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
7-73