Memobus Ascii Mode - YASKAWA MP920 User Manual

B.2.3

MEMOBUS ASCII Mode

With ASCII communications, RTU communications data is converted to ASCII before
being sent and received.
The following diagram shows an example of RTU to ASCII conversion. As shown in the
example, 8-bit application data is converted to two ASCII characters (7 bits).
With the MEMOBUS format, the code (":") showing the start of the data is added in front of
the data, and the code ("CL" or "LF") showing the end of the data is added after the data.
LRC will be the error check.
7
Slave address
Function code
Start No.
No. of data items
CRC-16
0 7
02H ;
Slave address
03H
00H
Function code
6BH
00H
03H Start No.
74H
24H
No. of data items
LRC
CR
LF
B-25
B.2 MEMOBUS Messages
0
Message start mark
3AH
30H
32H
30H
33H
30H
30H
RTU mode 8-bit data is
36H
converted to ASCII
42H
characters.
30H
30H
30H
33H
ASCII mode error check
38H
44H
0DH
Message end mark
0AH
B