System information

General Reference Guide IO Servers Configuration
RG-001-0-EN ver 1.5 eWON® - 20/03/2009 - ©ACT'L sa Page 88
5.3 Modbus IO server
5.3.1 Introduction
The MODBUS IO Server setup is the standard remote IO communication setup of the eWON. It is used to configure:
• The eWON as a Modbus RTU master.
• The eWON as a Modbus TCP slave and master.
The first feature (Modbus TCP slave) is specific to the MODBUS IO server; it is actually designed to provide access to eWON Tag values and,
unlike all the other IO servers, for interfacing field values with the eWON.
The second feature (MODBUS Master) is the actual IO server feature that provides an interface to the field values as a common IO server.
The eWON MODBUS IO server will give access to values in equipments having a MODBUS interface.
The interface can be:
• RS485 – MODBUS RTU protocol will be used
• ETHERNET/PPP – MODBUS TCP protocol will be used.
The eWON can mix access to MODBUS RTU and MODBUS TCP, depending on the way the Tag address is defined.
5.3.2 Setup
5.3.2.1 Setup for eWON Server
Figure 74: Modbus TCP Server configuration
This page defines the eWON configuration when used as a Modbus TCP slave.
As described in the Tag configuration paragraph, each Tag can be published to Modbus TCP so that a Modbus TCP can read their values.
This setup screen defines the eWON address, and globally enables or disables the Modbus TCP slave feature.
5.3.2.2 Setup for eWON IO server and Gateway - COM Setup
Figure 75: Modbus communications configuration
If more than one Serial port are available, you must choose on which COM the modbus request will be sent.
This configuration part defines the RS485 setup. The four first fields are used to define the baud rate, parity, number of stop bits and the reply
timeout (in msec – usually 1000 msec).
Warning: When there are multiple IO servers using potentially the serial line, then the unused IO server must be Cleared or the
baudrate must be set to Disabled.
eWON Server Properties Description
eWON server enabled
Globally enables or disables the Modbus TCP Server feature. If disabled, then any request
from a Modbus TCP master will be rejected, even if Tags are published.
Modbus TCP Unit address
This feature is used by some gateway but can usually be left to 1 because Modbus TCP
appears as a point to point connection.
Table 56: eWON server configuration - eWON as Modbus TCP slave