Chapter 9 Communications
7O1
Odd
parity
Start
bit
01
2
3456
Stop
bit
7-data bits
10-bits character frame
11-bit character frame (For 8-bit character)
8N2
Start
bit
01
2
3456
Stop
bit
8-data bits
11-bits character frame
Stop
bit
7
8E1
Start
bit
01
2
3456
Stop
bit
8-data bits
11-bits character frame
7
Even
parity
8O1
Start
bit
01
2
3456
Stop
bit
8-data bits
11-bits character frame
7
Odd
parity
Communication Protocol
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 (0)
Contents of data: n word = n x 2-byte consists of n x 4 ASCII codes
n
10
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 communication protocol of ASCII mode starts from a start character ’: ’ (3AH). ADR is 1-
byte consists of 2 ASCII codes. CR (Carriage Return) and LF (Line Feed) is a special sequence
of characters signifying the end. There are communication address, function code, contents
of data and LRC (Longitudinal Redundancy Check) between Start and End.
9-6 Revision January 2011
Call 1(800)985-6929 for Sales
Call 1(800)985-6929 for Sales
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