2 Modbus protocol description
12
2.4.1 Reading n words
This function is used to read n words, starting from a specific address.
Data query
Response
Example
This example is about reading the time (hours, minutes, and seconds). Starting from address
0x11E6, it is stored in three words.
Chapter 7 "Modbus address tables", page 59
Slave address Function code
0x03 or 0x04
Address of
first word
Number of words Checksum CRC
1 byte 1 byte 2 bytes 2 bytes 2 bytes
Slave address Function code
0x03 or 0x04
Number of
bytes read
Word value(s) Checksum CRC
1 byte 1 byte 1 byte x bytes 2 bytes
Hex code for the data query:
01 03 11 E6 00 03 E1 00
Slave Function code Address of
1st word
Number of
words
CRC
Hex code for the response:
01 03 06 00 0A 00 03 00 01 88 B4
Slave Function code Bytes
read
10 03 01 CRC
Hours Minutes Seconds
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