Fail-Safe Electronic Modules
8.1 8 /16 F-DI DC24V PROFIsafe Digital Electronic Module
ET 200pro Distributed I/O System - Fail-Safe Modules
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Operating Instructions, 05/2007, A5E00394073-02
WARNING
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 F-DI Modules: 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 4
Yes*
Yes
Short circuit of DI 0 with DI 5
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.
