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MELSEC-Q
4 FUNCTIONS
4.1.2 Global control functions
Global control contains the four functions of SYNC, UNSYNC, FREEZE, and
UNFREEZE, which are functions that are used to maintain/cancel slave I/O for which
multicast communication is conducted at the same time.
The slaves that execute the global control function are those located in one or more
groups of the eight groups. The group No. of the group containing the slaves is set by
the configurator. In the QJ71PB92D the group can be arbitrary specified and the global
control commands transmitted using multicast communication. This makes is possible
to select a slave and conduct global control.
Master
PROFIBUS-DP network
Group 1
Group 5
The global control function is executed using X, Y, and FROM/TO instructions from the
sequence program.
(1) Service SYNC, UNSYNC
Master
(SYNC transmission to group 1)
Output data
SYNC
(Group 1)
(Group 2)
(Group 1)
(Group 1)
Slave 1
Slave 2
Slave 3
Slave n
Output image memory: Data is always refreshed using polling.
<During UNSYNC execution/default>The output image memory value is output unchanged
(normal condition)
<During SYNC execution>The output image memory value is only output once during the
SYNC service timing.
Service SYNC (issued in the same group)
