Synchronization Mode; Synchronization Modes Of The Servo Drive - Delta ASDA-A3 Series User Manual

EtherCAT Mode

13.2.2 Synchronization mode

13.2.2.1 Synchronization modes of the servo drive

13
The servo drive supports two synchronization modes: Free Run mode and DC-Synchronous
mode. Note that the Free Run mode is defined as a synchronous mode in the EtherCAT
specification established by the EtherCAT Technology Group (ETG).
Free Run mode (Asynchronous)
Actually, the master and slave stations run asynchronously in the Free Run mode. The clock of
the slave runs independently of the clock of the master. In other words, the clocks are not
synchronized. The command and feedback transmissions between the master and slave are
based on a sequential order instead of a precise time synchronization. For example, the master
sends a PDO at the time T1, and the slave receives the PDO at the time T2 after the SM2 event.
Controller
(master)
Network
T2
Slave
Local
timer
DC-Synchronous mode (SYNC0 synchronization)
There is precise time synchronization between the master and slave stations in the
DC-Synchronous mode. The master periodically executes the control program and sends PDO
packets at a fixed time according to the distributed clocks (DC), and then transmits the
command to the slave and receives the feedback from the slave. The slave receives and
updates the PDO data at a fixed time according to the distributed clocks.
Controller
(master)
Network
Slave
Note: Delay = P3.009.Z * (T/10) (µs)
13-14
Master application task
Master user shift time
T1
Frame
T2
Cycle time = 1 ms Cycle time = 1 ms
Slave App Task Slave App Task
Master application task
Master user shift time
Frame
Sync0
Cycle time (T)
Delay
Slave App
Master application task
Master user shift time
T1
U Frame
T2
SM2 event
Cycle time = 1 ms
Slave App Task
Master application task
U
Sync0
Cycle time (T)
SM2 event
Delay
Slave App
Master application task
T1
U
T2 T2
SM2 event
Cycle time = 1 ms Cycle time = 1 ms
Slave App Task Slave App Task
Master application task
Master user shift time
Frame U
Sync0
Cycle time (T)
SM2 event
Delay
Slave App
ASDA-A3
Frame U
SM2 event
Frame