User guide

eWON 500-2001-4001-4002 User Guide - eWON Configuration
eWON 500®2001®4001®4002® Version 4_3_0 - User Guide - 10/5/05 - ©ACT'L sa - Page 56
4.4 Tag Setup
4.4.1 Tag definition: Introduction
The eWON SCADA features are based on:
• The configurable monitoring of Tags
• The execution of scripts
All the variables monitored by the eWON are defined as "Tags". A Tag is a Boolean or Float value changing with time
and coming from a data-source.
Typical data-sources are:
• eWON internal Inputs/Outputs
• Remote Modbus Input/Outputs
• eWON memory Inputs/Outputs (updated by script)
The data source is called an "IO Server". An IO Server is the interface between the changing value and the eWON monitoring engine.
It is a kind of driver. Any variable from any data source must have a common representation for all IO Servers in order to define common interface
in the eWON.
The data-source representation in the eWON uses 3 fields for the definition of a Tag:
• The IO Server Name
• The Topic name
• The Item Name
A Tag’s data-source will be uniquely identified with these 3 parameters.
For example, the MODBUS IO Server needs to poll registers or coils from a slave, so it uses an item name representation to define the register
type, register address and slave address.
(Example "40001,5" => Where 4 means read write register, 0001 is the register number and 5 is the slave Modbus address).
A description of the different IO Server syntax is given in Annex. Once a Tag is configured with its Server Name, Topic Name and Item Name,
it is given a Tag name that will be used everywhere in the eWON.
IO Server name
Is a kind of driver name. For each IO Server there is a specific Topic Name and Item Name
syntax.
The following drivers are available: MODBUS, EWON, MEM, NETMPI, UNITE (Unitelway),
DF1, FINS and S5-AS511.
Topic Name
Is used to group items inside an IO Server, for example the memory IO Server uses the blank
topic ("") and the retentive topic ("ret"). All Tags of the MEM IO Server defined in the "ret" topic
will have their value saved and restored when the eWON boots.
All IO servers do not use Topic Name. In that case Topic Name must be empty.
Item Name
The item name is a string of characters; its syntax is specific to each IO Server.
The Item Name describes the physical variable to monitor using the IO Server.
Table 35: Tag’s data-source parameters