Omron CS1D DUPLEX SYSTEM - 10-2009 Operation Manual page 152

Duplex CPU Units
116
Cyclic Operations
Active CPU Unit
Startup processing
Duplex initialization
Common cyclic
processing
User program
execution
Synchronized
instructions (See note.)
Beginning of duplex synchronization
I/O refreshing
Duplex bus check
Peripheral servicing
Duplex refreshing
Waiting for end of duplex synchronization
Note These instructions include IORF(097) (I/O REFRESH), DLINK(226) (CPU
BUS UNIT I/O REFRESH), IORD(222) (INTELLIGENT I/O READ),
IOWR(223) (INTELLIGENT I/O WRITE), PID(190) (PID), RXD(235)
(RECEIVE), FREAD(700) (READ DATA FILE), and FWRIT(701) (WRITE
DATA FILE).
The following table shows the processing related to duplex operation. For
details, refer to SECTION 9 CPU Unit Operation and the Cycle Time.
Processing
Startup processing
Duplex initialization
Beginning of duplex
synchronization and
Waiting for end of
duplex synchroniza-
tion
Standby CPU Unit
Startup processing
Duplex initialization
Common cyclic
processing
User program
execution
Synchronized
processing
Synchronized
instructions (See note.)
Transfer processing
Transfer processing
Peripheral servicing
Transfer processing
Duplex-related processing
Duplex status is checked (i.e., whether the Unit status is active
or standby).
Data is transferred from the active CPU Unit to the standby
CPU Unit, and verified. (Details are provided below.)
In a Duplex CPU System, synchronization processing is exe-
cuted in order to coordinate the timing of active and standby
CPU Unit operations.
Section 3-1