Specifications
7. Application Instructions
© DELTA ELECTRONICS, INC. ALL RIGHTS RESERVED
7-44
Content 0 1
b8
Start word
selection
none D1124
b9
The first end word
selection
none D1125
b10
The second end
word selection
none D1126
b15~b11 No definition
Ϩʳ Start character and end character of control characters will be defined
in the communication format of peripheral equipment when using RS
command. Start character and end character can be set in
D1124~D1125 by user or defined by machine. When users use M1126,
M1130, D1124~D1125 to set start and end character, b8~b9 of D1120
of RS485 communication protocol should be set to 1. Please refer to
the following chart for detail.
M1130
0 1
0
D1124: user define
D1125: user define
D1126: user define
D1124: H 0002
D1125: H 0003
D1126: H 0000ΰno settingα
M1126
1
D1124: user define
D1125: user define
D1126: user define
D1124: H 003A ΰ’:’α
D1125: H 000DΰCRα
D1126: H 000A ΰLFα
Ϩʳ Example for communication format setting:
Communication format: Baud rate 9600 7, N, 2
STX : Ϙ: ϙ
ETX1 : ϘCRϙ
EXT2 : ϘLFϙ
You can get the communication format H788 via check with chart and
write into D1120.
b15
b0
0000011110001000
788
D1120
0
Don t care
MOV H788 D1120
M1002
You should pay attention to special auxiliary relay M1126 and M1130 when
using STX, EXT1 and EXT2.
Ϩʳ M1143: ASCII / RTU mode selection. ON is RTU mode and OFF is
ASCII mode.
Take standard MODBUS format to explanation.
ASCII mode (M1143=OFF):
STX Start word = ‘: ’ (3AH)
Address Hi
Address Lo
Communication address:
8-bit address consists of 2 ASCII codes
Function Hi
Function Lo
Function code:
8-bit function code consists of 2 ASCII
codes
DATA (n-1)
…….
DATA 0
Data content:
nͪ8-bit data content consists of 2n ASCll
codes
LRC CHK Hi
LRC CHK Lo
LRC check sum:
8-bit check sum consists of 2 ASCll code
END Hi
END Lo
End character:
END Hi = CR (0DH), END Lo = LF(0AH)
Communication protocol is made of MODBUS ASCII(American
Standard Code for Information Interchange). Each byte consists of 2
ASCII characters. For example: a 1-byte data 64 Hex shown as ‘ 64’ in
ASCII, consists of ‘ 6’ (36Hex) and ‘ 4’ (34Hex).