Connection examples of safe inputs
108928_en_02
PHOENIX CONTACT
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Input to external 24 V
Yes
Symme
-
try viola
-
tion
2
No
The error is detected on a change in state, as the state only
changes in one channel.
– Change in state from “1” to “0”:
The faulty input remains at “1”. A “0” is transmitted in
the process data image of the affected inputs.
– Change in state from “0” to “1”:
A “0” is transmitted in the process data image of the
inputs, as the faulty input was not previously set to “0”.
Clock output that is not clocked
to external 24 V
No
None
No
The error is not detected.
Short circuit
Input to ground
Yes
Symme
-
try viola
-
tion
2
No
The error is detected in state “1” or on a change in state
from “0” to “1”, as the state only changes in one channel.
Clock output to ground
Yes
Short cir
-
cuit
No
The error is detected as a short circuit of the clock output.
The affected clock output is disabled.
External 24 V to ground
Yes
None
No
The error is detected as a change in state from “1” to “0”.
An unexpected change from “0” to “1” is possible.
Make sure that this change in state cannot restart the sys
-
tem unintentionally.
1
SF = safety function
2
Only applies when symmetry monitoring is active.
WARNING: Loss of the safety function
An accumulation of errors can result in the loss of the safety function.
•
Test the safety function at regular intervals to detect errors at an early stage.
Table 7
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5
2-channel equivalent, cross-circuit monitoring disabled: supply through a clock output or external supply [...]
Error type
Detec
-
tion
Diagnos
-
tics
Loss of
SF
1
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