TECHTOP TD20 Series Product Manual page 103

TD20 Series VFD
START
ADDR
CMD
Byte number
Data high bit of address 0004H
Data low bit of address 0004H
Data high bit of address 0005H
Data low bit of address 0005H
CRC CHK low bit
CRC CHK high bit
END
The meaning of the response is that:
ADDR = 01H means the command message is sent to the VFD with the address of 01H and ADDR
occupies one byte
CMD=03H means the message is received from the VFD to the master for the response of reading
command and CMD occupies one byte
"Byte number" means all byte number from the byte (excluding the byte) to CRC byte (excluding the
byte). 04 means there are 4 byte of data from the "byte number" to "CRC CHK low bit", which are "digital
address 0004H high bit", "digital address 0004H low bit", "digital address 0005H high bit" and "digital
address 0005H low bit".
There are 2 bytes stored in one data with the fact that the high bit is in the front and the low bit is in the
behind of the message, the data of data address 0004H is 1388H, and the data of data address 0005H is
0000H.
CRC occupies 2 bytes with the fact that the high bit is in the front and the low bit is in the behind.
7.3.2 Command code: 06H
06H (correspond to binary 0000 0110), write one word (Word)
The command means that the master write data to the VFD and one command can write one data other
than multiple dates. The effect is to change the working mode of the VFD.
For example, write 5000 (1388H) to 0004H from the VFD with the address of 02H, the frame structure is
as below:
RTU master command message (from the master to the VFD)
START
ADDR
CMD
High bit of writing data address
Low bit of writing data address
High bit of data content
Low bit of data content
CRC CHK low bit
T1-T2-T3-T4
01H
03H
04H
13H
88H
00H
00H
7EH
9DH
T1-T2-T3-T4
T1-T2-T3-T4
02H
06H
00H
04H
13H
88H
C5H
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Communication Protocol