LS Industrial Systems XGB Series - Page 30

Chapter 5 Protocols of Various Services
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(3) Function code 0x03: Read Holding Registers
(a) Request
Classification Size Range
Function code 1 byte 0x03
Start address 2 bytes 0x0000 ~ 0xFFFF
Number of input 2 bytes 0x0001 ~ 0x007D (125 words)
[Table 5-21] Function code 0x03 request frame
(b) Response
Classification Size Range
Function code 1 byte 0x01
Number of bytes 2 bytes 2 x N
Input status N x 2 bytes -
[Table 5-22] Function code 0x03 response frame
(c) Error
Classification Size Range
Function code 1 byte 0x83 (Function code + 0x80)
Exception code 1 byte 0x01,0x02,0x03,0x04
[Table 5-23] Function code 0x03 error frame
(d) Examples
Request frame Response frame
Classification HEX Classification HEX
Function code 0x03 Function code 0x03
Start address (Upper byte) 0x00 Number of bytes 0x06
Start address (Lower byte) 0x6B Word status (108) 0x02
Number of words (Upper byte) 0x00 Word status (108) 0x2B
Number of words (Lower byte) 0x03 Word status (109) 0x00
Word status (109) 0x00
Word status (110) 0x00
Word status (110) 0x64
[Table 5-24] Function code 0x03 frame examples
(4) Function code 0x04: Read Input Registers
(a) Request
Classification Size Range
Function code 1 byte 0x04
Start address 2 bytes 0x0000 ~ 0xFFFF
Number of input 2 bytes 0x0001 ~ 0x007D (125 words)
[Table 5-25] Function code 0x04 request frame
(b) Response
Classification Size Range
Function code 1 byte 0x04
Number of byte 2 bytes 2 x N
Input status N x 2 bytes -
[Table 5-26] Function code 0x04 response frame