Delta ASDA-B2 Series User Manual page 277

Chapter 8 Communications
 Communication Data Structure:
The data frame of two different communication modes is defined as follows:
ASCII Mode:
Start Start character': ' (3AH)
Slave address Communication address: 1-byte consists of 2 ASCII codes
Function Function code: 1-byte consists of 2 ASCII codes
DATA(n-1)
.......
Data content: n word = n x 2-byte consists of n x 4 ASCII codes, n10
DATA(0)
LRC Error checking: 1-byte consists of 2 ASCII codes
End 1 End code 1: (0DH)(CR)
End 0 End code 0: (0AH)(LF)
The start character of communication in ASCII mode is colon '：' (ASCII is 3AH), ADR is
the ASCII code of two characters. The end code is CR (Carriage Return) and LF (Line
Feed). And the communication address, function code, data content, error checking LRC
(Longitudinal Redundancy Check), etc. are between the start character and end code.
RTU Mode:
Start
Slave address
Function
DATA(n-1)
.......
DATA(0)
CRC
End 1
The start of communication in RTU (Remote Terminal Unit) mode is a silent interval. The
end of it is another silent interval. The communication address, function code, data content,
error checking CRC (Cyclical Redundancy Check), etc. are between the start and the end.
8-8
A silent interval of more than 10 ms
Communication address: 1-byte
Function code: 1-byte
Data content: n word = n x 2-byte, n  10
Error checking: 1-byte
A silent interval of more than 10ms
ASDA-B2
Revision May, 2018