Yaskawa Sigma-5 User Manual: MECHATROLINK-II Commands - Manual (Page 12)

1 MECHATROLINK-II Commands
1.1.4 Terminology
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1.1.4 Terminology
This section defines the terminology used in this manual.
(1) Transmission Cycle and Communications Cycle
„ Transmission Cycle:
The transmission cycle is the cycle in the MAC (Media Access Control) layer. It is the communications cycle
for physically sending data to the transmission path.
The transmission cycle is unaffected by the services provided by the application layer.
„ Communications Cycle:
The communications cycle is the cycle for application layer. The communications cycle is set to an integral
multiple of the transmission cycle.
(2) Synchronization Classification
MECHATROLINK-II commands include both synchronous and asynchronous commands.
• Synchronous Commands (Classification S):
For commands of this type, commands are sent and response are received every communications cycle.
A response to a command that has been sent to a slave station is received at the next communications cycle.
The WDT (Watchdog Timer) in the frames are refreshed and checked every communications cycle. Synchro-
nous commands can be used only during synchronous communications (Phase 3).
• Asynchronous Commands (Classification A):
For commands of this type, commands are sent asynchronously to the communications cycle.
Subsequent commands can be sent after confirming the completion of processing of the slave station that
received the command.
The WDT (Watchdog Timer) in the frames are not checked.