Mitsubishi Electric MELSEC iQ-R Series User Manual page 92

Configuration of number of multi-transaction queues
For multi-transactions, the next primary message is issued without waiting for the arrival of the prescribed secondary
message. (In the case of single transactions, the next transaction is never issued until a secondary message is sent for a
primary message. )
If interleaving (simultaneous processing of multiple transactions) is required, the number of multi-transaction queues should
be configured to two or more according to the communication specifications.
The following table shows the objectives and operations of each multi-transaction queue.
Item
Number of Multi-Transaction Queues For PLC
Transmission
Number of Transaction Queues For PLC
Transaction
Number of Multi-Transaction Queues For PLC
Receiving
■Operation when the "Number of Multi-Transaction Queues For PLC Transmission" has been
configured multiple times
Messages of the number specified by "Number of Multi-Transaction Queues For PLC Transmission" are sent simultaneously.
When the Number of Multi-Transaction Queues For PLC Transaction becomes full, messages that arrive later are
accumulated (interleaved) in the Number of Transaction Queues For PLC Transmission.
Programmable
controller CPU
Transmission request
relay A on
Transmission request
relay B on
Transmission request
relay C on
Precautions
If the Number of Transaction Queues For PLC Transaction becomes full, sending fails and later messages are discarded.
When "Number of Multi-Transaction Queues For PLC Transmission" has been set multiple times, configure "Number of
Transaction Queues For PLC Transmission" multiple times as well.
7 BASIC FUNCTIONS
90
7.7 Option Setting
Objective
Configure the number of primary messages that can
be sent simultaneously.
Configure the number of queued messages that can
be retained simultaneously.
Configure the number of received messages that
can be retained simultaneously.
Device
Operation
Messages are queued in the sending
transaction queue when the queue is full.
Any subsequent messages are discarded when
the queue is full. (Sending failure)
Any subsequent messages are aborted when
the queue is full.
SECS/GEM communication
software
Transmission
request A, B, and C
detection
Primary A
Primary B
Primary C
Host
The transmission
messages, A, B,
and C, are acquired.