Fail-Safe Modules
7.5 4/8 F-DI DC24V PROFIsafe Digital Electronic Module
ET 200S Distributed I/O System - Fail-Safe Modules
Installation and Operating Manual, 08/2008, A5E00103686-07
119
WARNING
To achieve SIL3/Category 3/PLe using this wiring, you must use a suitably qualified sensor.
Assignable Parameters for Application 2.1
Set the "1oo2 evaluation" at the corresponding input, and "Single-channel" at the "Type of
sensor interconnection" parameter. The default discrepancy time of 10 ms cannot be
modified.
You can activate or deactivate the "short-circuit test" parameter. For digital inputs connected
to an external supply, set the "Sensor supply" parameter for the corresponding digital input
to "external". The program will otherwise report a "short circuit" diagnostics event if the
"short-circuit test" is activated.
Specific Features of Fault Detection (Application 2.1)
The following table presents fault detection according to the sensor supply and the
parameter assignment for the short-circuit test:
Table 7- 20 EM 4/8 F-DI DC24V PROFIsafe: Fault detection (application 2.1)
Fault detection if ...
Example of fault
Internal sensor supply
and short-circuit test
are activated
Internal sensor supply
and short-circuit test
are deactivated
External sensor
supply
Short circuit in DI 0 with DI 1
no
no
no
Short circuit in DI 0 with DI 5
no
no
no
P-short circuit in DI 0
Yes
no
no
M-short circuit in DI 0
Yes*
Yes*
no
Discrepancy error
Yes
Yes
Yes
P-short circuit in sensor
supply 1
Yes
no
no
M-short circuit in sensor
supply 1, or sensor supply 2
defective
Yes
Yes
Yes
Short circuit in sensor supply
1 with sensor supply 2
Yes
no
no
Fault in read/test circuit
Yes
Yes
Yes
Supply voltage fault
Yes
Yes
Yes
*: 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, the wiring between the sensor and
input channel must be short circuit-proof.
