Astraada DRV-24 frequency inverters Communication protocol
97
Standard structure of ASCII frame:
START
‘:’ (0x3A)
Address Hi
Communication address:
8-bit address is formed by the combination of two ASCII
codes
Address Lo
Function Hi
Function code:
8-bit address is formed by the combination of two ASCII
codes
Function Lo
DATA
（
N-1
）
…
DATA
（
0
）
Data content:
nx8-bit data content is formed by combination of 2n (n≤16)
ASCII codes
LRC CHK Hi
LRC check code:
8-bit check code is formed by the combination of two ASCII
codes.
LRC CHK Lo
END Hi
End character:
END Hi=CR (0x0D), END Lo=LF (0x0A)
END Lo
7.2.3.1 ASCII mode check (LRC Check)
Check code (LRC Check) is the value combined of address and data content result. For instance, the
check code of above 2.2.2 communication message is: 0x02+0x06+0x00+0x08+0x13+0x88=0xAB,
then take the compliment of 2=0x55. Below is a simple LRC calculation function for user reference
(programed with C language):
Static unsigned char
LRC(auchMsg,usDataLen)
unsigned char *auchMsg;
unsigned short usDataLen;
{
unsigned char uchLRC=0;
while(usDataLen--)
=*+;
return((unsigned char)(~((char)uchLRC)));
}
7.3 Command code and communication data illustration
7.3.1 RTU mode
7.3.1.1 Command code:03H
03H
（
correspond to binary 0000 0011
）
,read N words
（
Word
）
(the Max. continuous reading is 16
words)
Command code 03H means that if the master read data from the inverter, the reading number
depends on the “data number” in the command code. The Max. Continuous reading number is 16
and the parameter address should be continuous. The byte length of every data is 2 (one word). The
following command format is illustrated by hex (a number with “H” means hex) and one hex
occupies one byte.
The command code is used to read the working stage of the inverter.
For example, read continuous 2 data content from0004H from the inverter with the address of 01H
(read the content of data address of 0004H and 0005H), the frame structure is as below:
RTU master command message (from the master to the inverter)
START
T1-T2-T3-T4
Summary of Contents for AS24DRV4075
Page 1: ...Operation Manual Astraada DRV 24 Frequency inverters ...
Page 2: ......
