FD67 Profibus-DP Manual
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7.3 Profibus
Diagnosis status modification of the FD67 System is reported to the DP master. The DP master then
requests the diagnostic information, which is supplied in the form of the diagnosis message described
below.
Some DP masters accept in standard configuration only diagnosis messages with a
maximum length of 32 bytes. If possible, this value should be set to the maximum
Profibus-DP supported length of 244 bytes. Otherwise, the max. length must be
limited by blinding channel-related diagnosis messages (Bus node parameters, see
chapter 8). In this case, a channel-related diagnosis is only reported in the form of a
collective bit in the station-related diagnosis.
The diagnosis model of Profibus DP distinguishes between three layers of diagnostic information.
A plaintext message is stored in the GSD file for each diagnosis. Diagnosis messages can be masked out
selectively via the bus node parameterization.
Example :
In an application, the actuator supply voltage is to be monitored for undervoltage, but no diagnosis is to
be generated when the actuator voltage is switched off, e.g. in an emergency stop situation.
Solution :
The parameter "No actuator supply" of the bus node is set to "Do not report'.
Result :
No diagnosis is generated if the actuator supply voltage is less than 12 V. If the voltage is between 12 V
and 18 V, the diagnosis "Undervoltage actuator supply" will be reported.
Station-related diagnosis
- Undervoltage measured at bus node
- Undervoltage measured at I/O module
- Communication fault
- etc.
ID-related diagnosis
- Information as to which modules have diagnostic capability
Channel-related diagnosis
- Short-circuit in the supply of a sensor
- Short-circuit to 0V or overload (actuator cut-off)
- Short-circuit to +24 V (actuator warning)
- Diagnosis according to DESINA
- etc.