Siemens SIMATIC NET DP/AS-i Link 20E Manual page 119

Slave diagnostics
With slave diagnostics, errors on PROFIBUS DP (for example parameter
assignment errors) and errors on the AS-Interface are signaled to the DP master.
In protected mode, the DP/AS-Interface Link 20E (DP/AS-i Link 20E) signals
"diagnostics" whenever the configuration on the AS-Interface is changed.
Configuration changes can be: when the voltage on the AS-Interface is too low
(AS-i Power Fail) and when configuration errors are detected (missing, incorrect or
existing but unconfigured AS-i slaves).
If the error is eliminated again on the AS-Interface, this is indicated by "leaving
diagnostic state" (bit 3 in the station status 1 set to "0").
The exact cause of the problem is entered in the device-related diagnostic
information − see Section 4.5.
In the configuration mode, errors on the AS-Interface are not indicated to the DP
master.
4.1 Overview
Notice
The DP/AS-i Link 20E only signals errors on the AS-Interface when it is operating
in protected mode and the diagnostic interrupt is enabled in the DP configuration.
Notice
If the AS-i voltage drops below 14 V, then no DP data exchange is possible due to
the lack of power supply. This means that no diagnostic message can be created
to signal that the AS-i power supply is too low. The DP master recognizes that the
DP/AS-i Link 20E has failed and indicates this problem to its user program.
Access mechanism
Read the manual of your DP master to find out the mechanisms you can use on
the DP master to access diagnostic information.
The following sections explain the content of the slave diagnostic information.
DP/AS-Interface Link 20E
Release 08/2008
C79000-G8976-C235−01
4
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