Modbus Reference Tables - GE RX3i User Manual

Chapter 8. Modbus/TCP Server
tables for Modbus data. The following table shows how each Modbus table is mapped to the PACSystems
reference tables.

Modbus Reference Tables

Modbus File Modbus Holding
Access Register Table
(6xxxx) (4xxxx)
--- ---
--- ---
--- ---
--- 1 – 32640
(16-bit words)
F1,R1 – ---
F525,R2880
(16-bit words)
Modbus File Access Table
The Modbus File Access table is mapped exclusively to PACSystems %W memory.
Applicable Functions
▪
Read File Record
▪
Write File Record
Translating %W Reference Addresses
To find the PACSystems %W memory address equivalent of a Modbus File and Record:
%W = 10,000 (F-1) + R
To find the Modbus File and Record equivalent of a PACSystems %W memory address:
Figure 53: Calculations for Modbus File and Record %W Memory Address
If you use the Modbus function Write File Record, and specify multiple record
sections, the first N-1 sections will be written to the server's PLC reference
memory, even if an error prevents the writing of the last section.
136 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual
Modbus Input
Register Table
(3xxxx)
---
1 – 32640
(16-bit words)
---
---
---
W-1
File = + 1
10,000
Record = W – (10,000 (F – 1))
Modbus Input Modbus Coil
Discrete Table Table
(1xxxx) (0xxxx)
1 – 32768 ---
(bits)
--- ---
--- 1 – 32768
(bits)
--- ---
--- ---
(Discard any fractional portion;
round the result downward to
the next integer value).
Caution
PACSystems
Reference Tables
%I1 – 32768
(bits)
%AI1 – 32640
(16-bit words)
%Q1 – 32768
(bits)
%R1 – 32640
(16-bit words)
%W1 –5,242,880
(16-bit words)
GFK-2224Q