(
1-7-1 format, odd parity)
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Start
bit
Parity
bit
Stop
bit
(
1-7-1 format, even parity)
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Start
bit
Parity
bit
Stop
bit
11 characters box
（
For RTU
）
(
1-8-2 format, no parity)
Start
bit
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Stop
bit
Stop
bit
(
1-8-1 format, odd parity)
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Start
bit
Parity
bit
Stop
bit
(
1-8-1 format, even parity)
BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7
Start
bit
Even
parity
Stop
bit
Communications data structures
ASCII mode
Frame header
Start character=“：”（3AH）
Address Hi
Address： 8-bit address combined with two ASCII code
Address Lo
Function Hi
Function code：
8-bit address combined with two ASCII code
Function Lo
DATA
（
n - 1
）
Data content：
n * 8-bit data content combined with 2 * n ASCII code, in which
high in front and low in post, n <= 4, 8 ASCII code as maximum
……………
DATA 0
LRC CHK Hi
LRC Check code
：
8 check code combined with two ASCII code
LRC CHK Lo
END Hi
End character：
END Hi = CR(0DH), END Lo = CR(0AH)
END
Larson Electronics, LLC
Phone:
Fax: (903) 498-3364
www.larsonelectronics.com
44
of
52
VFD-1P-220.240-1HP-7A-DCM
(877) 348-9680