PROFIBUS
BC315080 Version: 2.1.0
Diagnosis type Description
Station-related Messages relating to the general operational readiness of a device such as
overtemperature or undervoltage
Module-related These messages indicate that diagnostic signals are pending within a specific I/O sub
range of the device (e.g.an 8bit output module)
Channel-related Here the cause of an error is related to a single input/output bit (channel), such asa
short circuit on output 2
The Beckhoff PROFIBUS slaves from theIPxxxx-B310, IL230x-B310 and IL230x-C310 series support the
PROFIBUS DP diagnostic functions. Assessment of the diagnostic data by means of the controller depends
on the support for the PROFIBUS master. Please refer to the device manuals for the master interfaces for
details of how to handle the diagnosis.
Sync and Freeze Mode
In addition to the user data traffic related to the device, which is automatically dealt with by DPM1, a DP
master has the option of sending control commands to one DP slave, to a group of them or to all of them at
the same time. These control commands are transmitted as Multicasts. These control commands can be
used to specify the sync and freeze operating modes, in order to synchronize the DP slave. They permit
event-controlled synchronization of the DP slaves.
The DP slaves start Sync mode when they receive a sync control command from the assigned DP master.
In this operating state, the outputs of all the addressed DP slaves are frozen at their current values. In the
following user data transmissions, the DP slaves store the output data, but the output states themselves
nevertheless remain unchanged. Only when the next sync control command is received from the master the
stored output data is switched through to the outputs. Sync operation is ended with an Unsync control
command.
A freeze control command similarly causes the addressed DP slaves to enter Freeze mode. In this operation
mode the states of the inputs are frozen at their current value. The input data is only updated again when the
DP master has sent the next freeze control command to the devices concerned. Freeze operation is ended
with an unfreeze command.
System behavior
The system behavior is also standardized in PROFIBUS DP, so that devices can to a large extent be
interchanged. It is largely determined by the operating state of the DPM1. This can either be controlled
locally, or over the bus by the project design device.
The following three major states are distinguished:
Operation mode Description
Stop There is no data traffic between the DPM1 and the DP slaves. The Bus Coupler only
addresses the Bus Terminals once after the power has been switched on (none of the
I/O LEDs are lit).
Clear The DPM1 reads the input information from the DP slaves, and maintains the outputs
of the DP slaves in a safe state (depending on the reaction to fieldbus errors, the
green I/O LED is lit and the outputs are set).
Operate The DPM1 is in a data transfer phase. In the course of cyclic data traffic the inputs of
the DP slaves are read and the output information is transmitted to the DP slaves (the
green I/O LED is lit).
The DPM1 sends its local status at a configurable time interval using a multicast command cyclically to all
the DP slaves that have been assigned to it. The reaction that the system has to the occurrence of an error
during the DPM1's data transfer phase, suchas the failure of aDP slave, is specified in the Auto-Clear
operating parameter. If this parameter is set to True, then the DPM1 switches the outputs of all the
associated DP slaves into a safe state as soon as one DP slave is no longer ready for the transfer of user
data. The DPM1 then switches into the Clear state. If the parameter is False then the DPM1 remains in the
operating state even after a fault, and the user can himself specify the system's reaction.
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