Siemens SIMATIC Operating Instructions

Fail-Safe Electronic Modules
8.3 F -Switch PROFIsafe Digital Electronic Module
ET 200pro Distributed I/O System - Fail-Safe Modules
128 Operating Instructions, 05/2007, A5E00394073-02
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 8-28 F-Switch PROFIsafe Electronic Module: Fault Detection (Use Cases 3.1 and 3.2)
Fault detection with internal sensor supply and enabled
short-circuit test for ...
Example of Fault
Sensor 2-channel equivalent Sensor 2-channel
nonequivalent
Short circuit of DI 0 with DI 1 Yes* Yes*
Short circuit of DI 0 with DI 2 Yes* Yes
Short circuit of DI 0 with DI 3 Yes* Yes*
P-short circuit of DI 0 Yes Yes
M-short circuit of DI 0 Yes* Yes*
Discrepancy error Yes Yes
P-short circuit of Vs1 Yes Yes
M-short circuit of Vs1, or Vs2 defective Yes Yes
Short circuit of Vs1 with Vs2 Yes Yes
Fault in read/test circuit Yes Yes
Supply voltage fault Yes Yes
*: 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.
Requirements for Machine Protection Applications With Category 4
The following requirements apply to machine protection applications with Category 4:
● State-of-the-art wiring must be used between the sensors and the automation system or
between the automation system and the actuators to prevent short circuits.
● All short circuits listed in the above table are detected. Detection of a short circuit is
sufficient in this case, because two faults must exist for the short circuit to occur (both of
the short-circuited signal cables exhibit an insulation fault). Thus, a multiple short-circuit
analysis is not required.
Processes for detection of all short circuits are also permissible if individual short circuits are
not detected, provided:
● The short circuits do not cause corruption of read signals compared to the sensor signals
or
● The short circuits cause corruption of read signals compared to the sensor signals, but in
the direction that ensures safety.

Siemens SIMATIC Specifications

General

Product type designation	SIMATIC
CPU	Varies by model
Memory	Varies by model
Input/Output	Varies by model
Communication	Varies by model
Programming Language	STEP 7
Operating Temperature	0°C to 60°C (varies by model)
Protection Class	IP20
Category	Programmable Logic Controller (PLC)