Operation Of The Link Scan - Mitsubishi Electric CC-Link IE Basic Reference Manual

Operation of the link scan

This section describes the operation of the link scan.
MELSEC iQ-R, MELSEC-Q/L
After sending the requests to all of slave stations and subsequently receiving responses from all the slave stations, the master
station starts the next link scan. Link refresh is performed in END processing after receiving responses from all the slave
stations.
END
Program
St
END
Program
St
END
St: Scan time (sequence scan)
Ls: Link scan
END: END processing
 The master station sends a request to slave station 1 and slave station 2.
 Slave station 1 sends a response to the master station.
 Slave station 2 sends a response to the master station.
(1) Once the master station has received responses from slave station 1 and slave station 2, the master station starts the next link scan.
• The link scan operates separately from the operation of programs.
• If the scan time is smaller than link scan time, link refresh is not performed until the master station receives
responses from all slave stations.
• The link scan time may increase five times longer than the normal time depending on the processing load or
communication load of the master station. Set an appropriate time for the timeout time. ( Page 23 Data
flow of cyclic transmission,  Page 39 Link Scan Setting)
7 FUNCTIONS
28
7.1 Cyclic Transmission
Master station
Ò
Ó
Ls
(1)
Ò
Ó
Ls
(1)
Ò
Ó
Ls
(1)
Ò
Ó
Ls
(1)
Ò
Slave station 1
Ô
Ô
Ô
Ô
Slave station 2