25: DATA LINK COMMUNICATION
« FC4A MICROSMART USER’S MANUAL » 25-9
Refresh Mode
In the data link communication, the master station sends data to a slave station and receives data from the slave station one
after another. After receiving data from slave stations, the master station stores the data into data registers allocated to each
slave station. The process of updating data into data registers is called refresh. The master station refreshes the received
data in the separate refresh mode as illustrated below:
When the data link system contains the MicroSmart and MICRO
3
/MICRO
3
C, set the baud rate to 19200 bps and transmit/
receive data quantity to 2 words in the Function Area Settings for the MicroSmart to communicate with MICRO
3
/MICRO
3
C
stations.
Separate Refresh Mode Communication Sequence
The master station can communicate with only one slave station in one scan time. When a slave station receives a commu-
nication from the master station, the slave station returns data stored in data registers assigned for data link communica-
tion. When the maximum 31 slave stations are connected, the master station requires 31 scans to communicate with all
slave stations.
Both master and slave stations refresh communication data in the END processing at each station. When data refresh is
complete, communication completion special internal relays M8080 through M8116 (slave station communication com-
pletion relay) go on at the master station for one scan time after the data refresh. At each slave station, special internal
relay M8080 (communication completion relay) goes on.
When the master station completes communication with all slave stations, special internal relay M8117 (all slave station
communication completion relay) goes on at the master station for one scan time.
Mode Separate Refresh Mode
Master Station Scan Time
Since the master station refreshes received data at the END processing of the user
program, the scan time in the master station is affected.
Master Station Refresh Timing Data received from one slave station is refreshed at each END processing.
Applicable Master Station
MicroSmart, OpenNet Controller, MICRO
3
, MICRO
3
C, FA-3S (PF3S-SIF4)
Applicable Slave Station
MicroSmart, OpenNet Controller, MICRO
3
, MICRO
3
C, FA-3S (PF3S-SIF4)
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