AS-Interface Analyser
Using the Analyser
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Subject to reasonable modifications due to technical advances.
Printed in Germany
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23.
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Therefore the protocol can be used
• as an overview of the actual state,
• as a test certificate of a new net,
• as a control and planning instrument for preventing maintenance work,
• for documentation of conscious or unconscious changes.
Such a protocol of the starting situation of the facility is very useful if subsequent
changes must be examined.
7.3
Error Diagnostics in the Network
The analyser can identify or at least isolate errors in the AS-Interface net. In most
cases the online statistics either with a current measurement or by a long-term test
is sufficient for this purpose. With PC attached the number of sent telegrams ex-
ceeds the largest representable number (11 digits) after a year principally. Then
the counter stops. A even finer analysis is possible with the trace mode by clever
use of trigger conditions and/or recording filter.
The analyser does no show only communication errors continuously but it exami-
nes the AS-Interface voltage at the position of the analyser although. These errors
can be seen In the "Overview", in the "Advanced Statistics" and in the "Consecu-
tive Error" immediately. In the trace they can be proven most easily over the setting
"Error" with trigger and filter.
However, communication errors can have a completely different cause and must
be interpreted:
7.3.1
Failure of a Slave
If a slave failed completely (before beginning of the measurement), so that no
communication is possible anymore, this slave is missing in all other representati-
ons of the analysers also. The analyser "does not see" this slave. The slave is mis-
sing in the configuration representation also. The master reports in the protected
mode, however, a configuration error. The read-out of the target configuration or
the comparison with earlier protocols clarify the situation.
The opposite applies if e.g. the external connections of a module are defective. In
this case the communication via AS-Interface is perfect, and the slave is represen-
ted green. In the data mode, however, the reaction of the application to the trans-
ferred in- or output data can be identified and the error can be identified.
7.3.2
Error by External Disturbances
Usually errors by external disturbances result from electromagnetic stray effects
e.g. by switching an engine or by electric discharge in the environment. In such
cases using the help of the "Overview with Hold Time" (adjusted with short holding
time) you can frequently show which timing correlation arises wit an event. This
proves that the change in the traffic light representation is synchronous to certain
facility conditions of the application or the environment.
An external source of disturbance is proven by the synchronous occurrence with
certain events. Such disturbances, however, are very rare with AS-Interface if the
net is correctly built. Their most frequent physical cause is an earth fault in the net
if they arise. Due to the functional principle of the analyser it cannot identify the
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