EGW1-IA3-MB-DF1 – Modbus TCP a DF1 User’s Manual
Exemys
www.exemys.com
Rev. 1
15
4
Operating modes
4.1
Modbus TCP a DF1 converter
Protocol conversion is based on tables that store the mapping between incoming requests (using
Modbus TCP protocol) and PLC data areas. Table translation applies for internal memory, but is not used
for Inputs/Outputs.
As a factory default , many newer PLCs (such as FlexLogix and ControlLogix) do not provide compatibility
with the type of request issued by the EGW1-MB-DF1. However, they do provide a mechanism to make
them downwards-compatible with other PLCs and with the EGW1-MB-DF1. Please refer to Appendix E if
you are attempting to connect one of the PLCs above to the EGW1-MB-DF1.
Henceforth, a real situation is proposed. It might differ slightly from your actual configuration, though we
think of an study case as the best way to get in touch with your new gateway.
There is PLC that runs a program. We want to make some data available to one Modbus TCP master by
means of the EGW1-MB-DF1. These boards have the following I/O capacities:
Table 1 - IO Capacity
Module
Feature
Capacity
1
16 Digital Inputs
1 word
2
32 Digital Outputs
2 words
3
4 Analog Outputs
4 words
4
32 Digital Inputs
2 words
It is desired to access not only I/O data, but it is also important to read some words, contained in two N
Files (File Numbers 7 and 10) and some read/write bit variables, contained in one B File, whose File
Number is 3. First, we check the internal tables are clean, by clicking on the Translation Tables link,
located on the left frame.
