KROHNE C95 CI EN - Manual (Page 30)

S
2 bytes
CRC 16
Slave
number
1 byte 1 byte 2 bytes
Function
3 or 4
CRC 16
1st word
MSB
address
LSB
Number
MSB
of words
LSB
2 bytes 2 bytes
Slave
number
1 byte 1 byte 1 byte 2 bytes
Function
3 or 4
CRC 16
Number
of bytes
read
Response pattern :
1st word
MSB
value
LSB
2 bytes
2nd word
MSB
value
LSB
2 bytes
Slave
number
1 byte 1 byte 2 bytes
Function
16
CRC 16
1st word
address
Nbr of
words to
be enfor.
Writing of N words : Function N°16 :
Request pattern :
Value of the words
to be enforced
2 bytes 2 bytes
Number
of words
to be enf.
2 bytes
Nbr of
bytes to
be enfor.
1 byte n bytes
Slave
number
1 byte 1 byte 1 byte
Function
16
1st word
address
Response pattern :
2 bytes
CRC 16
Slave
number
1 byte 1 byte 2 bytes
Function
6
CRC 16
Word
address
Writing of 1 word : Function N°6 :
Request pattern :
2 bytes
Value of
word to
be enfor.
2 bytes
Value of
word to
be enfor.
2 bytes
Slave
number
1 byte 1 byte 2 bytes
Function
6
Word
address
2 bytes
CRC 16
Slave
number
1 byte 1 byte 1 byte
Function
reques-
ted with
MSB=1
Error
code
Response pattern :
Exception pattern :
Values of the error codes :
1 : Function code unknown
2 : Address incorrect
3 : Data incorrect
9 : Writing impossible
Request pattern :
254 03
0 0 0 0 0 0 0 0
CRC 16 0 206
9.3 Reading in double integer format :
Example : Reading of the displayed measure
Request :
0 2
Address Reading
of n words
Slave
number
byte 3
0 0 0 0 0 0 0 0
byte 4
0 0 0 1 0 0 11
byte 1
1 0 0 0 1 0 0 0
byte 2
0
Sign : 0 positive
1 negative
0 19 136
Number of words
254 3 4 19
•• Response with a positive measure :
136 0 CRC 16 0
Measure value :
measure
byte 1 byte 2 byte 3 byte 4 2 bytes
11111111
byte 3
11111111
byte 4
111 0 11 0 0
byte 1
0 1111 0 0 0
byte 2
Sign : 1 negative : inverting of bits and adding of 1.
Measure = byte 3 x 2563 + byte 4 x 2562+ byte 1 x 256 + byte 2
= 0 x 2563 + 0 x 2562 + 19 x 256 + 136
= 5000
Reading of address 120 => decimal point = 2 => displayed meas. 50.00
254 3 4 236
•• Response with a negative measure :
120 255 CRC 16 255
measure
byte 1 byte 2 byte 3 byte 4 2 bytes
9.2 Description of born Modbus functions :
Reading of N words : Function n°3