Specifications

64
Schneider Electric
The Modbus Protocol (continued)
Note: In this case the "word" represents 2 bytes or 16 bits..
Read n words: function 3 or 4
b Query.
b Response.
Example:
Read words 805 to 80A of slave no. 2.
b Query.
b Response.
b Function 3: read output words or internal
bits.
b Function 4: read input words.
b The number of words to read should
be y 125.
E52364E52365E52366E52367
Slave no. 3 or 4
Address of the
first word to read:
Number of words
to read:
n
125 :
CRC 16
MSB* MSB* LSB*LSB* LSB* MSB*
1 b
y
te 1 b
y
te 2 b
y
tes 2 b
y
tes 2 b
y
tes
1 byte 1 byte 1 byte
2 bytes
2 bytes
2 bytes
Slave no. 3 or 4
Number of
bytes read
CRC 16
Value of first
word
MSB* MSB* LSB*LSB* LSB* MSB
*
Value of last
word
CRC 16
02 03 0805 0006
Value of word 805
CRC 16
Value of word 80A
02 03 OC XXXX YYYY
Guide to Integration
Modbus / Jbus