BBH SMX 12-2 - The following diagnoses for input sensors can generally be used for the safety related assessment of the entire system:

Installation manual
HB-37350-810-01-51F-EN SMX Installation manual.docx Page 60 of 234
Version: 50F
The following diagnoses for input sensors can generally be used for the safety related
assessment of the entire system:
Input element
characteristic
Parameterized /
operational tests
DC
Definition of measure
Note
Cross
-shorting test
With time
-out
Start test
Cyclic test during operation
Single-channel
O
O
>60
Cyclic test pulse by dynamic
change of input signals
A sufficiently high
test rate must be
ensured.
X
90
Cyclic test pulse by dynamic
change of input signals
Only effective if
pulse assignment
is active
X
O
O
90-99
Cyclic test pulse by dynamic
change of input signals
DC depending on
frequency of start
/ cyclic test
DC = 90 test only
in > 4 week
intervals
DC = 99 test at
least 1 x day / or
100-time request
rate
Dual channel
90
Cross-comparison of input
signals with dynamic test, if
short-circuits cannot be
detected (for multiple
inputs/outputs)
For fault exclusion
short-circuit up to
DC=99 possible
O
O
90-99
Cyclic test pulse by dynamic
change of input signals
DC depending on
frequency of start
/ cyclic test
X
99
Cross-comparison of input
signals with immediate and
intermediate results in the
logic (L) and temporal as
well as logic program
sequence monitoring and
detection of static failures
and short circuits (for
multiple inputs/outputs).
Only effective if
pulse assignment
is active
X
99
Plausibility test, e.g. use of
normally open and normally
closed contacts = non-
equivalent signal comparison
of input elements.
Only effective in
connection with
activated time-out
function for input
element