Address Configuration - GE RX3i User Manual

Modbus Holding Register Table
The Modbus Holding Register table is mapped exclusively to the CPU Register (%R) table.
Applicable Functions
▪
Read Multiple Registers
▪
Write Multiple Registers
▪
Write Single Register
▪
Mask Write Register
▪
Read/Write Multiple Registers
Modbus Input Register Table
The Modbus Input Register table is mapped exclusively to the CPU Analog Input (%AI) table.
Applicable Functions
▪
Read Input Registers
Modbus Input Discrete Table
The Modbus Input Discrete table is mapped exclusively to the CPU Discrete Input (%I) table.
Applicable Functions
▪
Read Input Discretes
Modbus Coil Table
The Modbus Coil table is mapped exclusively to the CPU Discrete Output (%Q) table.
Applicable Functions
▪
Read Coils
▪
Write Coils
▪
Write Single Coil

Address Configuration

Address mapping is done in the Machine Edition Hardware Configuration of the CPU. All Ethernet modules and
daughter-boards in the PLC use Modbus-to-PLC address mapping based on this one map. The Modbus/TCP
Server does not use COMMREQs to configure address mapping.
Each PLC memory area is mapped to an appropriate Modbus address space. On the Settings tab, Modbus
Address Space Mapping can be set to Standard Modbus Addressing or Disabled. If Modbus Address Space
Mapping is set to Standard, the Modbus/TCP Address Map tab displays the standard reference assignments.
Number Modbus Register
1 0xxxx – Coil Table
2 1xxxx Discrete Table
3 3xxxx Input Registers
4 4xxxx – Register Table
5 6yxxx – Internal Table
When Modbus Address Space Mapping is set to Disabled on the Settings tab, the Modbus/TCP Address Map tab
does not appear.
GFK-2224Q
Start Address End Address
1 32768
1 32768
1 64
1 1024
0 0
January 2017
Chapter 8. Modbus/TCP Server
PLC Memory Address
%Q00001
%I00001
%AI00001
%R00001
%W0001
Length
32768
32768
64
1024
0
137