GN-9371_2_3 User Manual
Page 85 of (110)
G-series GN-9371_2_3 PIO Rev. 1.02.docx
A.3.4 (0x04) Read Input Registers
This function code is used to read from 1 to approx. 125 contiguous input registers in a remote device. The
Request PDU specifies the starting register address and the number of registers. The register data in the
response message are packed as two bytes per register, with the binary contents right justified within each
byte. For each register, the first byte contains the high order bits and the second contains the low order bits.
•
Request
Field name
Example
RTU
Start of Frame
-
t1-t2-t3
Slave Address
0x07
0x07
Function Code
0x04
0x04
Starting Address Hi
0x00
0x00
Starting Address Lo
0x00
0x00
Quantity of Register Hi
0x00
0x00
Quantity of Register Lo
0x02
0x02
Error Check (CRC/LRC)
-
0x71, 0xAD
End of Frame
-
t1-t2-t3
•
Response
Field name
Example
RTU
Start of Frame
-
t1-t2-t3
Slave Address
0x07
0x07
Function Code
0x04
0x04
Byte Count
0x04
0x04
Input Register #0 Hi
0x00
0x00
Input Register #0 Lo
0x80
0x80
Input Register #1 Hi
0x00
0x00
Input Register #1 Lo
0x00
0x00
Error Check (CRC/LRC)
-
0x9C, 0x6C
End of Frame
-
t1-t2-t3
-
In case of address 0x0000, 0x0001 input register value: 0x0080, 0x0000.