MC Diag tab

TcIo-Statistics

max. TwinCAT-Jitter: Here, the maximum TwinCAT jitter is displayed; the measurement is reset as soon as the tab is no longer active.

min./max. Mapping Time or NC Access Time: Here, the minimum or maximum NC Access Time is displayed. Apart from the Mapping Time, this also contains the task runtime (provided that "IO at Task Start" for the highest-priority task linked to the FC310x (usually the NC task) is set). 

The NC Access Time should be greater than the sum of the two measured times (max. TwinCAT Jitter plus max. Mapping Time or (NC) Task Time), with a safety margin of approx. 10%.

max. FCxxxx Jitter: This is only relevant for Sync Mode = "disabled". If the value is greater than 5, real-time jitter will become excessive, and a more powerful PC should be used. If the associated (NC) task does not have the highest priority, the maximum FCxxxx jitter can also be larger. This should be avoided.

FC310x-Statistics

Since the PROFIBUS MC slaves should always be added to the FC310x device first, they are always addressed before the DP slaves in the DP cycle. This part of the DP cycle will be called Equi-Cycle below. If the Equi-Cycle becomes greater than the To-time of the MC slaves, the last MC slaves at the FC310x device 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.

FC310x-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: This counter is only relevant during Sync mode "disabled" and will increment in case of excessive jitter of the TwinCAT task which the DP cycle uses for synchronization (this may happen, for example, if the DP cycle is not synchronized with the highest-priority task). If the associated (NC) task does not have the highest priority, this counter can also increment. This should be avoided.

To-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 for all MC slaves is calculated with 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 (from TwinCAT 2.8)

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").