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CHAPTER 4 DEVICES
4
4.4 Link Direct Device
(b) Reading
The link device ranges of network modules can be read.
Writing or reading data by using a link direct device is allowed for only one network module that is on the same network.
If two or more network modules are mounted on the same network, a network module with the lowest slot number is the
target of writing or reading by the link direct device.
For example, if network modules set as station numbers 1 and 2 are mounted on network number 1 as shown in below,
station number 2 is the target of the link direct device.
(3) Differences between link direct devices and link refresh
For network parameters, common parameters, and network refresh parameters, refer to the following.
• Details: Manual for each network module
• Setting method: Operating manual for the programming tool used
Item Link direct device Link refresh
Description on
programs
Link relay
J \K4B0 or higher
B0 or higher
Link register
J \W0 or higher
W0 or higher
Link special relay
J \K4SB0 or higher
SB0 or higher
Link special register
J \SW0 or higher
SW0 or higher
Number of steps 2 steps 1 step
Range of network module access
J\0 to J\3FFF
Range specified by refresh parameters
Guaranteed access data integrity 2 word (32-bit) units
Station
No.2
Station
No.1
Network No.1
Writing/reading using link direct devices not allowed
Writing/reading using link direct devices allowed
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