Beckhoff EL6731 Documentation page 95

Parameterization and commissioning
EL6731 Failed Counter
Sync-Failed-Counter
This counter will increment if TwinCAT task and DP cycle are not synchronized with each other. This may
happen during start-up of the TwinCAT system, after which this counter should no longer increment. If the
associated (NC) task does not have the highest priority, this counter can also increment. This should be
avoided.
Time-Control-Failed-Counter
This counter will increment if the PROFIBUS was not free at the time of the DP cycle start. Possible causes
are bus faults, non-existent device, a second master or a safety time that is too small.
PLL-Overflow/Underflow Counter
Not relevant for EL6731.
MC Statistics
For each MC slave the To-time specifies when, relative to the DP cycle start, the slave should accept the
outputs received from the master. The MC slaves can be synchronized with each other, if the same To value
is set for all MC slaves. However, this value must be equal or greater than the Equi-Cycle Time plus a safety
margin of approx. 200 µs. The To-time is calculated for all MC slaves via the button "Calc. Equi-Times" (see
above).
calc. To-Reserve: This contains the calculated To-reserve (To-time - Equi-Cycle Time)
min./max. To-Reserve: Here, the min. or max. To-reserve is measured.
max. GC jitter
Here, the maximum jitter of the DP cycle is measured (GC for global control telegram, which is always sent
at the start of a cycle). During start-up, the jitter may be somewhat greater, in the steady state it should not
exceed 1 µs (for Sync mode "Sync Master") or 2 µs (for Sync mode "Disabled").
EL6731 Version: 2.8 95