Safety engineering
Device modules
Safe inputs
1
30
EDS94AYAF EN 1.0
Contact function test
Note!
Make sure that an internal contact function test is carried out at the safe
inputs:
Safe input in the ON state
ƒ A LOW level at one channel puts the input in the OFF state. The discrepancy
monitoring starts simultaneously.
ƒ A LOW level must be detected at both channels within the discrepancy time,
otherwise a discrepancy error will be reported.
ƒ To be able to acknowledge the discrepancy error, a LOW level must be
detected before at both channels.
Safe input in the OFF state
ƒ A HIGH level at one channel starts the discrepancy monitoring.
ƒ A HIGH level must be detected at both channels within the discrepancy
time, otherwise a discrepancy error will be reported.
ƒ To be able to acknowledge the discrepancy error, a HIGH level must be
detected before at both channels.
Switch both channels
to ON state
Switch both channels
to OFF state
One channel in
ON state
One channel in
OFF state
Value of safe input:
OFF state
Value of safe input:
OFF state
Value of safe input:
OFF state
Value of safe input:
ON state
Discrepancy monitoring Discrepancy monitoring
OFF state
ON state
SSP94SM355
Fig. 1−5 Status behaviour − contact function test
A
B
C
D
SSP94SM358_1
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