The diagnostic alarm is made up of the standard diagnosis according to PROFIBUS-DP
protocol and the user-specific diagnosis. The first six octets of the diagnostic alarm are as-
signed to the standard diagnosis, essentially providing a statement about the state of the cy-
clic connection. Special attention is given to the DIAG.ext bit (octet 1). The slave uses this bit to
indicate to the master that the output data are invalid. As a result, the master interrupts the
cyclic data exchange to read out the diagnostic data. The master first returns to cyclic data
exchange when the DIAG.ext bit is reset by the slave.
If, however, the DIAG.ext bit is set to 0, the existing data are treated as status information by
the system. For the Type 3730-4 Positioner, this behavior can be determined by the
FEATURE_SELECT parameter. By selecting the option “DIA_MAINTENANCE_ALARM sets
DIAG_EXT bit“, the DIAG_EXT bit is set when the DIA_MAINTENANCE_ALARM bit has been
determined. Deactivate this option if all the data of the positioner should be used as status in-
formation.
On using the Profile 3.01 the DIAG_EXT bit can be set when the measured value status has
be assigned to BAD_DEVICE_FAILURE. This only happens when the following errors, which
lead to device failure, occur:
4
Test calculation
4
Fatal error
4
Program loading error
4
No production calibration
4
Hardware
4
i/p converter
On using the 'Condensed status and diagnostic messages' extension, the assignment can be
selected as required.
The first four bytes of the manufacturer-specific diagnosis are used for diagnostic alarms ac-
cording to Profile 3.01. On using the 'Condensed status and diagnostic messages' extension,
these condensed diagnostic alarms are also included in these bytes. The manufacturer-spe-
cific diagnosis listed in the following table is transmitted in the eleventh byte and above. The
contents of both parameters of the Physical Block, DIAGNOSIS and DIAGNOSIS_EXT, are
sent.
Standard diagnosis according to PROFIBUS-DP protocol
Regardless of whether the positioner has been integrated according to Profile 3.01 or using
manufacturer specifications, the diagnosis can be restricted to six bytes. For this purpose, the
FEATURE_SELECT parameter provides the option “Use DP standard diagnosis (6 bytes)” (see
page 54).
30 KH 8384-4 EN
Measured value status and valve diagnostics
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