Fig. 18 Fc310X Is Sync Master - Beckhoff FC3102 Documentation

FC310x as master
Sync Master
The synchronization signal is generated by the FC310x, the PC synchronizes itself with the FC310x (jitter of
the PROFIBUS cycle approx. 1 µs).
Fig. 18: FC310x is Sync Master
The NC Access Time specifies by how much the TwinCAT cycle is shifted towards the PROFIBUS cycle.
Setting of Equidistant Times
The Calculate Equi-Times button (TwinCAT 2.8: see FC310x [} 40] tab, TwinCAT 2.9: see MC [} 52] tab)
can be used to automatically set all equidistant parameters. The only parameter that may possibly have to
be adjusted later is the NC Access Time, because this depends on the maximum TwinCAT jitter and on the
maximum mapping time. This in turn depends on all the devices, so that adding and linking boxes to other
devices has the effect that it may nevertheless be necessary to change the NC Access Time for an
unchanged device. If "I/O not at task start" is selected (see the Synchronization [} 12] chapter), then the NC
Access Time also depends on the task runtime. To avoid having to manually adjust the NC Access Time
every time the Calculate Equi-Times button is pressed, the ratio of NC Access Time to Cycle Time can be
specified (set to 15% in delivery state).
Disabled (PC is Sync Master) or Sync Master
The NC Access Time must be greater than the maximum TwinCAT jitter plus the maximum mapping time,
plus, if "I/O not at task start" is selected for whichever task linked to the FC310x has the highest priority, it's
task runtime.
Diagnostics of Equidistant Times
The EquiDiag [} 46] tab (TwinCAT 2.8) or MC-Diag [} 56] tab (TwinCAT 2.9) in the System Manager can
be used for diagnosing the equidistance times, or this can be done via ADS in the control program (see
chapter Master diagnostics [} 20]).
FC3101 and FC3102 Version: 3.0 27