Kinco FV20 Series - RTU Mode; ASCII Mode

103
103
Modbus use “Big Endian” of encoder mode,which means sending data with high byte in front and low byte
behind.
1). RTU mode
In RTU mode,there must be a idle of at least 3.5 characters between two frames.It use CRC-16 for data
check.
Following is an example for read the parameter of internal register 0101(A1.01) from No.5 slave.
Request frame：
Slave
address
Function
code
Data
Checksum
Register address
Length
0x05
0x03
0x01
0x01
0x00
0x01
0xD5
0xB2
Response frame：
Slave
address
Function
code
Data
Checksum
Responselength
Register content
0x05
0x03
0x02
0x13
0x88
0x44
0xD2
Therein, checksum is CRC value.
2). ASCII mode
In ASCII mode , characters are used to start and end a frame. The colon “0x3A” is used to flag the start of a
message and each message is ended with a “0x0D,0x0D” combination. Except frame header and end of
frame,all other messages are coded in hexadecimal values, represented with readable ASCII characters.
Only the characters 0...9 and A...F are used for coding. Herein the data use LRC as error checksum.
Following is an example for writing value 4000(0x0FA0) into the parameter of internal register 0201(A2.01)
from No.5 slave.
Request frame：
Frame
header
Slave
address
Function
code
Data
Check
code
Frame trail
Register address
Setting value
Character
：
0
5
0
6
0
2
0
1
0
F
A
0
4
3
CR
LF
ASCII
3A
30
31
30
36
30
32
30
31
30
46
41
30
34
33
0D
0A
Therein, the check code is LRC checksum,which value is equal to the complement of
（05+06+02+01+0x0F+0xA0）.
Response frame：
Frame
header
Slave
address
Function
code
Data
Check
code
Frame trail
Register address
Setting value
Character
：
0
5
0
6
0
2
0
1
0
F
A
0
4
3
CR
LF
ASCII
3A
30
31
30
36
30
32
30
31
30
46
41
30
34
33
0D
0A
VFD can set different delay time for response according to different application.For RTU mode,the actual
delay time for response is 3.5 characters interval at least.For ASCII mode,the actual delay time for response
is 1 ms at least.