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MELSEC
9 UTILITY OPERATIONS
(1) Link Device Access Method
Item Description
Link Refresh
Makes access to the MELSECNET/H driver buffer.
Data in the MELSECNET/H driver buffer and the refresh data storage area on
the MELSECNET/H board are updated by link refresh.
When secured data handling is specified with the control station parameter,
data consistency
1
of link device data is ensured.
Personal computer
MELSECNET/H board
Refresh data
storage area
User
program
drive buffer
Reading
Writing
Link refresh
MELSECNET/H
Direct Access
Provided for MELSECNET/10 compatibility.
Makes access to the refresh data storage area on the MELSECNET/H board.
Data consistency
1
of link device data is not ensured even if secured data
handling is specified with the control station parameter.
MELSECNET/H board
Personal computer
Reading
Writing
Refresh data
storage area
User
program
1: Data consistency function prevents 2-word (32 bits) link data (e.g. current value of a positioning module) from being
divided into two 1-word (16bits) data (old and new data) by certain cyclic transmission timing.
(a) Link Refresh Interval
Link refresh is performed at intervals of the specified value multiplied by link
scan time. The load of the link refresh processing by the MELSECNET/H
driver on the PC decrease in inverse proportion to this value.
The specified interval value changes the delay time, which is duration from
when link device data arrive at the refresh data storage area on the
MELSECNET/H board until they are read out into the user program.
(Refer to POINT.)
Summary of Contents for Q80BD-J71BR11
Page 2: ......
Page 24: ...A 22 A 22 MEMO ...
Page 50: ...4 6 4 6 MELSEC 4 FUNCTION MEMO ...
Page 92: ...6 36 6 36 MELSEC 6 PROCEDURE AND SETTINGS UP TO THE POINT OF OPERATION MEMO ...
Page 132: ...10 2 10 2 MELSEC 10 MELSEC DATA LINK LIBRARY MEMO 10 ...
Page 138: ...11 6 11 6 MELSEC 11 PROGRAMMING MEMO ...
Page 164: ...12 26 12 26 MELSEC 12 APPLICATION FUNCTIONS MEMO ...
Page 166: ...13 2 13 2 MELSEC 13 ERROR CODE MEMO 13 ...
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