Mitsubishi Electric MELSEC-Q Series - Precautions for Link Dedicated Instructions

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9.2.2 Precautions for link dedicated instructions
The following explains precautions for using link dedicated instructions.
(1) When executing multiple link dedicated instructions at the same time
When executing multiple link dedicated instructions at the same time, make sure that the channels for them are
not duplicated.
Link dedicated instructions with identical channel settings cannot be used at the same time.
If execution of these instructions is attempted at the same time, they will not be executed.
(a) Channels
Channel is a network module area where data treated by link dedicated instructions are stored.
Using multiple channels allows simultaneous access from the own station to multiple other stations, and
simultaneous reading and writing to the same network module.
(b) Number of channels and number of simultaneously-executable link dedicated
instructions
A CC-Link IE Controller Network module has ten channels that are available for link dedicated instructions
*1
Up to ten instructions can be simultaneously executed if channels are not duplicated.
*1 Channels 9 and 10 are used for READ/SREAD/WRITE/SWRITE instructions.
(c) Example of channel use
• When the own station simultaneously accesses other stations (READ instruction, WRITE instruction),
change the channel of the own station for each request target.
• When making access mutually between the own station and another station (SEND instruction, RECV
instruction), change the channel of the own station for each link dedicated instruction.
● When the same channel is to be set for different tasks, access to one of other stations first and after completion of the
access, access to another.
The completion status of a dedicated instruction can be confirmed with the completion device of the instruction.
● Channels used for RECV instructions cannot be used for any other instructions.
Channels used for other instructions must be changed.
Channel 1: Write to station No.1
Station No.3
(Own station)
Station No.1
(Other station)
Station No.2
(Other station)
Channel 2: Read from station No.1
Channel 3: Write to station No.2
Channel 4: Read from station No.2
Channel 1
Channel 2
Channel 3
Channel 4
WRITE
READ
WRITE
READ
Station No.1
(own station)
Channel 1: For send Channel 1: For receiveChannel 1
SEND
Station No.2
(other station)
Channel 1
RECV
Channel 3: For receive Channel 3: For sendChannel 3
RECV
Channel 3
SEND