Fuji Electric ALPHA5 Smart, User Manual

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CHAPTER 13 RS-485 COMMUNICATIONS
13-4
Modbus RTU Communications
13
13.1.2 Communication Specifications
Item Specifications Remarks
(PA is a parameter No.)
Electric I/F RS-485
Communication
speed
38400
／
19200
／
9600
／
115200 bps
Set by parameter PA2_73
Synchronization
method
Asynchronous (UART)
Communication
method
Semi-duplex communication
Transmission format Master-slave (servo amplifier) = 1:N
(1

N

31)
Max. 31 units connected
simultaneously
Connection cable
LAN cable (straight) or equivalent
Cable length
(recommneded)
Entire extended length:
100 m or less (up to 38400 bps)
40 m or less (115200 bps)
Length between stations:
20 m or less
Terminator treatment Master side
:100 Ω
recommended
Slave side : Unnecessary
Comm
uni
cati
on
Character
configuration
Start bit : 1 bit
Data length : 8 bits
Parity : Even/Odd/None
Stop bit : 1 or 2 bits
Set by parameter PA2_93
Communications
protocol Compliant with Modbus RTU protocol
Communications
mode RTU mode The ASCII mode is not
supported.
Station number 0: Broadcast
1-31: Slave station No. Set by parameter PA2_72
Function code (FC) 1(01h): Read out coil data
3(03h): Read out various data
5(05h): Write in single coil data
8(08h): Maintenance (echo back)
15(0Fh): Write in coil data
16(10h): Write in various data
23(17h): Read out/write in various data Responses other than those in
the left cell are exceptional
responses (improper FC).
Error check method CRC-16 method
Message length Variable length Max. 200 bytes
Protocol
Frame
synchronization
method Timing synchronization Frames are initialized if time
data for three characters are
absent.
It is recommended to use the RS-232C - RS-422 converter (model: NW0H-CNV) for the use of 1:1
communications between the master and the slave (servo amplifier). Do not use it for multiple unit
connection.