Modbus Configuration
This page contains information on how the I/O modules are currently mapped in the Modbus process image and how the general Modbus register assignment is structured.
 
I/O Mapping
  Modbus Register [word addresses]
I/O Module Order Number input (RO) output (WO) output (RW) I/O access
1750-4xx3.0 - 3.7--RO
2750-4xx3.8 - 3.15--RO
3750-653/003-0000 - 20 - 2512 - 514RO

  Modbus Coils [bit addresses]
I/O Module Order Number input (RO) output (WO) output (RW) I/O access
1750-4xx0 - 7--RO
2750-4xx8 - 15--RO
3750-653/003-000----
 
General Modbus Mapping
  Input Register (FC3, FC4, FC23)
Modbus address Description
0x0000 - 0x00FFphysical input data
0x0100 - 0x01FFplc output variables data
0x0200 - 0x02FFphysical output data
0x0300 - 0x03FFplc input variables data
0x1000 - 0x2FFFspecial register data
0x3000 - 0x5FFFretain data
0x6000 - 0x62FBphysical input data
0x7000 - 0x72FBphysical output data
0x8000 - 0x8FFFretain data

  Output Register (FC6, FC16, FC22, FC23)
Modbus address Description
0x0000 - 0x00FFphysical output data
0x0100 - 0x01FFplc input variables data
0x0200 - 0x02FFphysical output data
0x0300 - 0x03FFplc input variables data
0x1000 - 0x2FFFspecial register data
0x3000 - 0x5FFFretain data
0x6000 - 0x62FBphysical output data
0x7000 - 0x72FBphysical output data
0x8000 - 0x8FFFretain data

  Digital Input (FC1, FC2)
Modbus address Description
0x0000 - 0x01FFphysical input data
0x0200 - 0x03FFphysical output data
0x1000 - 0x1FFFplc output variables data
0x2000 - 0x2FFFplc input variables data
0x3000 - 0x7FFFretain data
0x8000 - 0x85F7physical input data
0x9000 - 0x95F7physical output data

  Digital Output (FC5, FC15)
Modbus address Description
0x0000 - 0x01FFphysical output data
0x0200 - 0x03FFphysical output data
0x1000 - 0x1FFFplc input variables data
0x2000 - 0x2FFFplc input variables data
0x3000 - 0x7FFFretain data
0x8000 - 0x85F7physical output data
0x9000 - 0x95F7physical output data