Maxsine EP3 AC Series, User Manual

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Chapter 6 Communication functions
186
6.3 MODBUS communication protocol
When RS-485 serial communication is used, every servo drive should be set its servo drive
station by P300 parameter in advance. Computer or upper controller implements control for servo
drive according to the station number. The baudrate needs to refer to the communication
parameter of upper controller to set parameter P301, in which MODBUS can use the following
two modes: ASCII
（ American Standard Code for information interchange ） mode or RTU （ Remote
Terminal Unit
）
mode. The user can set the needed communication protocol in the parameter P320.
There is explanation for MODBUS communication as follows:
The encoding meaning
ASCII mode:
Every 8 bits data consists of two ASCII character. For example: one 1byte data 64H
(hexadecimal notation), presented by ASCII “64”, contains ‘6’ASCII code (36H) and ‘4’ ASCII
code (34H).
The ASCII code of figure 0 to 9 and letter A to F, is in the following chart.
Character sign ‘0’ ‘1’ ‘2’ ‘3’ ‘4’ ‘5’ ‘6’ ‘7’
Corresponding
ASCII code 30H 31H 32H 33H 34H 35H 36H 37H
Character sign ‘8’ ‘9’ ‘A’ ‘B’ ‘C’ ‘D’ ‘E’ ‘F’
Corresponding
ASCII code 38H 39H 41H 42H 43H 44H 45H 46H
RTU mode:
Every 8bits data consists of two 4bits hexadecimal characters. For example: one 1byte data
is 64H.
Character structure
：
10bits character frame (used for 8bits character without verification)
8, N, 1
11bits character frame (used for 8bits character with verification)
8
，
E
，
1