HEIDENHAIN PROFIBUS-DP (DPV0) - Manual (Page 45)

Encoder and Gateway functionality, DPV0
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5.6.1 Diagnostic Header
The header byte specifies the length of the encoder diagnostics
including the header byte. The format of the transmission length
is hexadecimal. For the PROFIBUS-DP encoder of class 1 the
length of the encoder-specific diagnostic data is 10 bytes (0Ahex).
DDLM_Slave_Diag
Octet 7
Alarms 7 6 5-0
Data 0 0 xxh
Set to 00 Length incl. header
Extended diagnosis
Table 21 Diagnostic header
5.6.2 Alarms
Alarm is generated by the device when failure occurs which
effects the position value. Octet 8 in the diagnostic function
(DDLM_Slave_Diag) indicates the status of the alarms.
Additional alarms for device class 2 are addedin the diagnostic
octet 17.
If an alarm is given, the Ext_Diag bit and the Stat_Diag bit in
the diagnostic function are set to high and remain high until
the alarm is cleared and the encoder can provide a correct
position value. Alarms are cleared when the functionality is
within the specifi- cation and the position value is correct.
Note: Not every encoder supports every alarm. For
encoders of class 2 the diagnostic information
“supported alarms” (see Chapter 5.6.8) makes it
possible to find out which individual alarm bits are
supported.