Estun ETS Series - MODBUS Protocol Details

ETS Series AC Servo User's Manual
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6.3 MODBUS Communication Protocol
There are two modes for MODBUS communication: ASCII (American Standard Code for information interchange) mode
and RTU (Remote Terminal Unit) mode.
The next section describes the two communication modes.
6.3.1 Code Meaning
ASCII Mode：
Every 8-bit data is consisted by two ASCII characters. For example: One 1-byte data 64 H（Hexadecimal expression）is
expressed as ASCII code ‘64’, which contains ‘6’ as ASCII code 36
H
and ‘4’as ASCII code 34
H
.
ASCII code for number 0 to 9、character A to F are as follows:
Character
‘0’
‘1’
‘2’
‘3’
‘4’
‘5’
‘6’
‘7’
ASCII Code
30
H
31
H
32
H
33
H
34
H
35
H
36
H
37
H
Character
‘8’
‘9’
‘A’
‘B’
‘C’
‘D’
‘E’
‘F’
ASCII Code
38
H
39
H
41
H
42
H
43
H
44
H
45
H
46
H
RTU Mode：
Every 8-bit data is consisted by two 4-bit hexadecimal data, that is to say, a normal hexadecimal data. For example:
decimal data 100 can be expressed as 64
H
by 1-byte RTU data.
Data Structure：
10-bit character form（7-bit data）
Start
bit
0 1 2 3 4 5 6
Stop
bit
Stop
bit
7-data bits
10- bits character frame
Pn700.1=0：7，N，2（Modbus，ASCII）
Start
bit
0 1 2 3 4 5 6
Even
parity
Stop
bit
7-data bits
10- bits character frame
Pn700.1=1：7，E，1（Modbus，ASCII）
Start
bit
0 1 2 3 4 5 6
Odd
parity
Stop
bit
7-data bits
10- bits character frame
Pn700.1=2：7，O，1（Modbus，ASCII）
11-bit character form（8-bit data）