Fail-Safe Modules
7.5 4/8 F-DI DC24V PROFIsafe Digital Electronic Module
ET 200S Distributed I/O System - Fail-Safe Modules
122
Installation and Operating Manual, 08/2008, A5E00103686-07
Specific Features of Fault Detection (Application 2.2)
The table below lists the fault detection according to the sensor supply and the parameter
assignment for the short-circuit test:
Table 7- 21 EM 4/8 F-DI DC24V PROFIsafe: Fault Detection (Application 2.2)
Fault detection if ...
Example of fault
Internal sensor supply and
short-circuit test are
deactivated
External sensor supply
Short circuit in DI 0 with DI 1
Yes*
Yes*
Short circuit in DI 0 with DI 4
no
no
Short circuit in DI 0 with DI 5
Yes*
Yes*
P-short circuit in DI 0
Yes*
Yes*
M-short circuit in DI 0
Yes*
Yes*
Discrepancy error
Yes
Yes
P-short circuit in sensor supply 1
no
no
M-short circuit in sensor supply 1, or
sensor supply 2 defective
Yes
Yes
Short circuit in sensor supply 1 with
sensor supply 2
no
no
Fault in read/test circuit
Yes
Yes
Supply voltage fault
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.
Wiring Diagram for Application 2.3 - Connecting a Nonequivalent Sensor to Two Nonequivalent
Channels
A nonequivalent connection of a 2-channel sensor is connected to two inputs of the F-
module for each process signal (1oo2 evaluation).
Alternatively, two one-channel sensors can be connected via two channels non-equivalently
(see figure "Wiring diagram EM 4/8 F-DI DC24V - two one-Channel sensors connected via
two channels nonequivalently, internal sensor supply"). In this case, the same process
variable is acquired with two mechanically separate sensors.
The left-hand channels on the F-module (DI0 through DI3) supply the wanted signals. If no
faults are detected, these signals will be available in the process image for inputs on the F-
CPU.
Note
If you power the sensors from the F-DI module, you must use the internal sensor supply Vs1.
Connection to Vs2 is not possible.
