Beckhoff EL6731 Documentation page 118

Parameterization and commissioning
soon as the highest priority task has transferred data once, and the DP connection for the corresponding DP
slave has been established, the master cyclically (with the highest priority assigned task) sends one
Data_Exchange telegram to each of the corresponding slaves.
In addition, the Operate Delay and Clear Mode settings (see Fault Settings [} 89] dialog) can be used to
specify when the master switches from "Clear" state (outputs are set to 0 or safe state (Fail_Safe = 1 in the
GSD file)) to "Operate" state (outputs correspond to the outputs transferred by the task). The Operate Delay
specifies the minimum length of time for which the master should remain in the "Clear" state following the
first transfer of data. As has been described above, the Clear mode specifies whether the master changes
into or remains in the "Clear" state if a slave in general or an MC slave in particular fails.
Shut-down behavior
The reaction to the stopping of the TwinCAT system is exactly the same as has been described above in the
"Failure of the Host" section; the DP connections to all slaves are removed, and the master logs itself off
from the bus.
5.1.8.3 Master Diagnostics
Diagnostic Inputs
The EL6731 features various diagnostic variables, which describe the state of the terminal and the Profibus
and can be linked in the PLC:
Fig. 120: Diagnostic inputs for EL6731 in the TwinCAT tree
Error
Shows the number of slaves with which data exchange could not take place in the last cycle. The box status
(BoxState) of the slaves should only be checked if this value is not equal to 0.
ActualModulo
Indicates the current modulo. This variable is only of significance if the slaves are prioritized (see the Slave
Prioritization/Multiple DP Cycles [} 129] section)
DiagFlag
Indicates whether the card's master diagnostic information has changed. It can then be read via ADS [} 42]
by the controller program, after that the "DiagFlag" variable is reset.
Master Diagnostics Data
The master diagnostic data can be read by ADS [} 42]:
ADS-Read parameters
Net-ID
Port
IndexGroup
IndexOffset
Length
Data
The master diagnostic data has the following structure:
118
Meaning
Net-ID of the master (see the device's ADS [} 92]
tab)
200
0x0000F100
offset within the diagnosis data
Length of the diagnostic data that is to be read
Diagnostic data
Version: 2.8 EL6731