BECKHOFF BK7300 - Manual (Page 29)

MODBUS
BK7300 25
Writing an Analogue Output (Function 6)
PRESET SINGLE
REGISTER Function 6 can be used to access the output process image and the
interface.
The first analogue output of slave number 11 is written with function 6. The
analogue outputs begin at offset 0x0800 (hex). Here again the offset
always describes a word. This means offset 0x0803 refers to the fourth
word in the output process image.
Query
Byte Name Example RTU ASCII
Start frame „:“ 0x3A
Slave address 11 0x0B „0B“ 0x30, 0x42
Function code 6 0x06 „06“ 0x30, 0x36
Start address high 8 0x08 „08“ 0x30, 0x38
Start address low 0 0x00 „00“ 0x30, 0x30
Data high 63 0x3F „3F“ 0x33, 0x46
Data low 255 0xFF „FF“ 0x46, 0x46
Error Check
LRC / CRC
0xDA
0xB0 „A9“ 0x41, 0x39
End of frame t1-t2-t3 CRLF 0xD, 0xA
Response
The coupler answers with the same telegram.
Byte Name Example RTU ASCII
Start frame „:“ 0x3A
Slave address 11 0x0B „0B“ 0x30, 0x42
Function code 6 0x06 „06“ 0x30, 0x36
Start address high 8 0x08 „08“ 0x30, 0x38
Start address low 0 0x00 „00“ 0x30, 0x30
Data high 63 0x3F „3F“ 0x33, 0x46
Data low 255 0xFF „FF“ 0x46, 0x46
Error Check
LRC / CRC
0xDA
0xB0 „A9“ 0x41, 0x39
End of frame t1-t2-t3 CRLF 0xD, 0xA