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CHAPTER 10 DEDICATED INSTRUCTIONS
10
10.2 Precautions for Dedicated Instructions
10.2.1 Precautions for link dedicated instructions
10.2 Precautions for Dedicated Instructions
10.2.1 Precautions for link dedicated instructions
The following describes precautions when using link dedicated instructions.
(1) Changing data specified for dedicated instructions
Do not change each data (such as control data) until a dedicated instruction operation is completed.
(2) When a dedicated instruction cannot be completed
Check if the master/local module is in the online mode.
Under the offline mode, the instruction is not executed.
(3) Executing multiple link dedicated instructions simultaneously
When executing multiple link dedicated instructions simultaneously, make sure that the channels for the
instructions are not duplicated. Link dedicated instructions with the same channel cannot be executed
simultaneously. To use the same channel for multiple link dedicated instructions, execute one after completion of
another. The completion status of the dedicated instruction can be checked by the completion device of the
dedicated instruction.
(a) Channel
A channel is an area of a network module where data handled by a link dedicated instruction is stored. By
using multiple channels, it is possible to simultaneously access from the own station to other stations or
concurrently read from and write to the same network module.
(b) Number of channels
The master/local module has 2 channels that can be used for link dedicated instructions. By using 2 channels
simultaneously, two instructions can be executed at the same time.
(c) Application example of channels
• Simultaneous access to other stations from the own station
Use a different own station channel for each request destination.
Channel 1: Write to station No. 1
Station No. 0
(Own station)
Station No. 1
(Other station)
Station No. 2
(Other station)
Channel 2: Write to station No. 2
Channel 1
Channel 2
WRITE
WRITE