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MELSEC-Q
6 PROGRAMMING
6.2.2 Block guarantee of cyclic data per station
Since link refresh is performed by handshaking between the CPU and network modules,
cyclic data integrity is assured in units of stations.
The Block guarantee of cyclic data per station is a function that prevents link data
consisting of two words (32 bits), such as a current value of a positioning module, from
being divided into new and old data in units of one word (16 bits).
As shown below, set the send and receive parameters as needed.
These settings can be made using the common parameters (supplementary settings)
only for the remote master station.
• Default: Disabled
Network range assignments Supplementary settings
By selecting both [Block send data assurance per station] and [Block receive data
assurance per station], an interlock for the link data between the stations to be set
becomes unnecessary.
Network module LW
CPU module device W
Refresh A
Refresh B
Updated portion
of refresh A
Refresh C
Updated portion
of refresh B
Updated portion
of refresh C
Station number 1
Station number 2
(Host)
Station number 3
Station number 4
Data assured
Data assured
Data assured
Data assured
<Precautions>
(1) In order to enable the block guarantee per station, it is necessary to set the
refresh parameters. (Refer to Section 5.1.5.)
(2) It is not necessary to set the block guarantee of cyclic data per station for remote
I/O stations.
POINT
For the transmission delay time calculation for the case where the Block
send/receive data assurance per station is set enabled, refer to Section 3.3.2 (1) (a)
and (2) (a) POINT.