Pepperl+Fuchs FieldConnex HD2-DM-A Manual page 90

Measured Values / Parameters
quirements. If the jitter level exceeds 3.2 µs a final warning will be indi-
cated.
Type
Precision
Measuring Range
Conforming standards value
Default value
Definition
Jitter is the deviation from the ideal timing of an event. In this case it is
deviation from the ideal zero crossing point of the transmitted signal
curve during the nominal bit duration, measured with respect to the pre-
vious zero crossing (reference event).
•
C L
Figure 9.2: Bit cell jitter
A
B
C
D
Causes
Jitter is composed of many factors, e. g.:
• cross talk
• electromagnetic interferences (EMI)
• simultaneous switching outputs
• device dependency
• bad wiring practice
Value definition
A high jitter level may cause communication problems and a lack of op-
Subject to reasonable modifications due to technical advances.
90
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V
1 bit time
C
A B
0.5 bit time
Reference event; first zero crossing point
Actual zero crossing point
Bit cell jitter, deviation from the ideal timing
Ideal zero crossing point
H D 2 - D M - A / D M - A M
Value
0.1 µs
0 µs ... 8 µs
3.2 µs
3.2 µs
D
0.5 bit time
t
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