3.                           IO & Device Communications



WebAccess provides a set of pre-built communication “drivers” that enable engineers and technicians to easily establish communications to automation devices including PLCs, controllers, DCS, DDC systems, other software packages, recorders, RTUs, IO, smart transmitters and other automation hardware.


These communication “drivers” are implemented using fill-in-the-blank forms that are actually web pages that interact with the WebAccess Database.  No programming is required. The steps, in summary, are:


1.      Start Internet Explorer Web Browser.

2.      Enter IP address of the Project Node.

3.      Use WebAccess Configuration.

4.      Open or Create a Project.

5.      Configure a SCADA node (the PC that will connect to the automation hardware).

6.      Configure a Comport for the SCADA Node (the physical or software link from the SCADA node to the automation Hardware).

7.      Configure a Device (determines the communications Protocol or Device Driver).

8.      Select Add Tag.  A tag is a piece of data read from or written to the PLC or automation device.

9.      Select a Parameter from the pull down list.  A parameter is a pre-built template to help build a Tag, with typical address, scale, conversion, etc.

10.   Assign a tagname, address, and conversion code.

11.  Optionally assign Alarms, Scaling, Engineering Units, Description and other features.


WebAccess drivers consist of the program that actually exchanges data with the device and a “database” which contains a description of what data the user wants to read and write to the device.