« FC4A MICROSMART USER’S MANUAL » 25-1
25: DATA LINK COMMUNICATION
Introduction
This chapter describes the data link communication function used to set up a distributed control system.
A data link communication system consists of one master station and a maximum of 31 slave stations, each station com-
prising a 16- or 24-I/O type MicroSmart CPU module or any slim type CPU module. When the data link communication is
enabled, the master station has 12 data registers assigned for each slave station, and each slave station has 12 data registers
for communication with the master station. Using these data registers, the master station can send and receive data of 6
data registers to and from each slave station. No particular program is required for sending or receiving data in the data
link communication system.
When data of inputs, outputs, internal relays, timers, counters, or shift registers are moved to data registers using the move
instructions in the user program, these data can also be exchanged between the master and slave stations.
The OpenNet Controller, MICRO
3
, MICRO
3
C, and FA-3S series PLCs can also be connected to the data link communica-
tion system.
The all-in-one 10-I/O type MicroSmart CPU module does not have data link communication capabilities.
Data Link Specifications
Electric Specifications Compliance with EIA-RS485
Baud Rate 19,200 or 38,400 bps
Synchronization
Start-stop synchronization
Start bit: 1
Data bits: 7
Parity: Even
Stop bit: 1
Communication Cable Shielded twisted pair cable, core wire 0.3 mm
2
Maximum Cable Length 200m (656 feet) total
Maximum Slave Stations 31 slave stations
Refresh Mode Separate refresh
Transmit/Receive Data 0 through 6 words each for transmission and receiving per slave station
Special Internal Relay
M8005-M8007: communication control and error
M8080-M8116: communication completion for each slave station
M8117: communication completion for all slave stations
Data Register D900-D1271: transmit/receive data
Special Data Register D8069-D8099: communication error code
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