MC Diag tab

EL6731 PLL

No longer relevant for EL6731.

EL6731 Statistics

Since the PROFIBUS MC slaves should always be added to the EL6731 first, they are always addressed before the DP slaves in the DP cycle. This part of the DP cycle is referred to as Equi cycle below. If the Equi cycle exceeds the To time of the MC slaves, the last MC slaves at the EL6731 will usually get a synchronization error (error 597 or 598 for Simodrive 611U).

max. repeats/equi cycle

This will show the maximum number of repeated Data_Exchange telegrams during an Equi-Cycle. This will extend the Equi-Cycle, usually no repetitions should occur (unless a bus plug was pulled or an MC slave was switched off).

min./max. equi cycle
Here, the minimum or maximum Equi-Cycle Time is displayed.

Equi cycle repeat counter
Here, the number of telegram repetitions within the Equi-Cycle is displayed.

Equi Cycle NoDxch Counter

Here, the number of occurrences is displayed, for which not all MC slaves were in data exchange during an Equi-Cycle.

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").