Fig. 20 Synchronization Mode - Beckhoff FC5101 Documentation

Parameterization and Commissioning
Fig. 20: Synchronization Mode
Slave
In slave mode, the card receives its time base from a SYNC master. The Sync Master is selected via the
corresponding field.
• Sync Master: PC Task. This is the default setting. The PC sets the timebase based on the TwinCAT
real-time. Depending on the setting, the task start (default for TwinCAT NC) or task end (default for
TwinCAT PLC) triggers the SYNC telegram.
• Sync Master: Balanced PC Task. In this operation mode, the sync cycle is also generated with the
accuracy of the PC time base on average. However, the interval between two SYNC telegrams is more
accurate than with the Sync Master "PC task":
◦ runtime differences (e.g. due to case-dependent program branches) are compensated,
◦ the FC510x card delays pending send telegrams until after the SYNC telegram,
◦ the individual SYNC distances are determined by the crystal-precise timer of the FC510x card.
If necessary, the card timer is readjusted in small steps to the PC timer if it the latter deviates from the card
timer by the value set in "PLL Sync Time".
In this mode, the sync telegram is delayed by the shift time relative to the completion of the TwinCAT task.
The shift time should be as small as possible in this mode, but sufficiently large to ensure that the TwinCAT
task can access the process data. The function "Calculate Equi-Times", which is triggered by clicking on the
corresponding button after the mappings have been created, helps to set the optimum shift time.
24 Version: 2.0 FC5101 and FC5102