26.9.2013
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AS-i 3.0 PROFIBUS Gateway in Stainless Steel
Advanced Diagnostics for AS-i Masters
9.4.2 Earth/Ground Fault Detector
An Earth/Ground Fault exists when the voltage
U
GND
(Nominal value of
U
GND
=0,5 U
AS-i
.) is outside of the following range:
10% U
AS-i
≤ U
GND
≤ 90% U
AS-i
This error substantially limits the noise immunity of the AS-i communication.
Ground faults are indicated on the master´s display as well as in AS-i Control
Tools.
9.4.3 Noise Detector
The noise detector detects AC voltages on AS-i, that are not initiated by an AS-i
master or AS-i slaves. These interference voltages can cause telegram distur-
bances.
A frequent cause are insufficiently shielded frequency inverters or improperly
routed cables.
Noises is indicated on the master´s display as well as in AS-i Control Tools.
9.4.4 Over-voltage Detector
Over-voltages are present if the conductors of an AS-i network that normally are
routed electrically symmetrical with respect to machine ground, are strongly elec-
trically raised. A cause can for example be startup procedures of large consum-
ers.
However, over-voltages do generally not interfere with the AS-i communication,
but can under certain circumstances cause incorrect sensor signals.
Over-voltages are indicated on the master´s display as well as in the AS-i Control
Tools.
Information!
To recognize ground faults the master must be grounded with its machine ground con-
nection.
Information!
A ground fault in one of the two networks of a double master in a version 1 power sup-
ply for two AS-i networks causes a ground fault in the other network as well because of
the the existing galvanic connection.
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