Tools for a Web based display from DDE info

J

John Kelley

I'm collecting all this stuff now via a DH+ to serial link with a KF-2, but.... eh... duh!! you know management folks. They want something they can click and see without firing up Excel or some other package.

I wondered if anyone had any experience incorporating this info into a dynamic web page that would be resident on the plants' ethernet. I've seen this done but never been involved in the specifics. I want the folks to have their IE Browser display the data... simple enough if you know what you're doing (Oh no!!)

I could take the simple way out and do a VB client on each workstation, but that wouldn't be any fun.

Any suggestions where to start would be appreciated.

Thanks...

John Kelley
Electrical Consultants, Inc
[email protected]

A

Aaron

Use VB to write DHTML or even ASP...

I

ind

Hi John,

I believe you must have thought of this, but just in case...

1. Create a database having tables to suite your requirement. you can use free/\$ databases, depends on your company's policies.

2. Author a few background tasks(executables) using C/C++/VB/PERL to poll your plc and populate the database. -OR- if you already have data in e-worksheets, nothing like it.

3. use HTML with embeded scripts (vb/java/perl) to fire SQL queries to the database, create html pages and throw them to the client (browser) to give your managements a view of whatever they are interested in.

What you need:
A. Webserver (Apache preferred)
B. Database s/w
(depends on volume of data: ms-access/oracle/mysql/postgresql...whole bunch of them are available)
C. programmers and time

PS:
There are people who do the same thing with a lot of complexity in software. You can have OPC servers/COM objects/COM interfaces, and a whole lot of stuff that is good, provides modularity, provides scalability etc.
But I believe that simplicity of software helps the people who have to maintain the system after the techies have gone away.

R

Raymond van der Tas

Obtaining data through a DDE link is a little old-fashioned. I would propose to at least implement a universal data access mechanism like OPC (ole for process control). You will find lots of OPC Servers on the market to allow exposing your AB data. (examples : Rockwell RS Linx, ICONICS AB OPC Server...)

In case you have some legacy data for which only a DDE server can be found, you can use a DDE-to-OPC server component. all your DDE links will then be available as regular OPC Tags.

Now all data is accessible for OPC Clients!

To present this data over an intranet/internet you can start the HMI package ICONICS GraphWorX32, draw your operator/manager graphics and hit the "Publish to WebServer" button.

The resulting HTML page contains a reference to the HMI ActiveX control and a reference to the process display you just created.

Any Web Browser can connect to the web server and present (read/write) the proces information. If required you can configure the security settings to protect certain process displays and OPC information againts unauthorised web visitors.

B

Bob Giblett

John,

The PC collecting the data can be set up as a Intranet webserver using Apache server (free download). Then you can create a simple web page with ActiveX controls embedded within the page so that the users can see the dynamic data using their Browsers. There are a number of companies that sell ActiveX virtual instrumentation displays at a moderate price.

Alternatively, use a package like Indusoft Web Studio as this can function both as a SCADA/HMI and webserver.

R

rddub

Check out GE Fanuc Cimplicity Offerings with the WebView Option. Also Wonderware offers Industrial Sequel with a Third Party Active Factory Package.

P

Philip Wong

We have an XML Server which can allows any remote Microsoft IE 5.0 web browser to display live data from PLC.

The XML Server is basically an HTTP Server which service XML requests for data from the web pages. Each web page waits for new data from the XML Server and update each graphic element based on the new data. HTTP requests using port 80 are not blocked by firewalls.

You have to be an expert in Javascript, XML (Extensible Markup Language), DHTML (Dynamic Hypertext Markup Language) and VML (Vector Markup Language) to construct your own web pages.

See http://www.ioserver.com/xmlcfg.htm for more information and a demonstration project.

Regards
Philip Wong
[email protected]
http://www.ioserver.com/

D

Dunn Jeff

John,

Any solution to your question really depends on the existing configuration
of your clients' system, but I hope the following might help.

The problem you describe is similar to a request from one of our clients.

The requirement we had was to provide plant information, in a tabular format, across the network. The network was already in place with several machines running NT4 Server.

We looked at several options:

SCADA Web client - ties the client into a single SCADA system, and as the
displays would not contain any graphic symbols this was not needed.

VB Application - simple to produce, but upgrades, and roll-out could be
difficult to control.

Web Based technology - very simple to control - source is resident on the Web Server, and as the Client would be using IE5 we could use VBScript for the main processing language. Everybody knows BASIC - don't they? Also, as the customer had a pc running NT4 Server, the Web Server (IIS4) was already available for installation onto the network - no extra software to be
purchased.

The final solution chosen was web based technology which threw up one more major problem - we had not used such technology previously.

After much reading of books and much writing of test software the final
configuration was chosen - namely the web site would be an IIS4 application
using Active Server Pages where the plant data is supplied via an ODBC
interface. The Active Server Page code resides and runs on the Web Server with little or no processing needed on the Client PC. An added advantage of this configuration is that should any complex processing be needed, then a VB ActiveX DLL can be written and incorporated into the web site.

As you will realise from the other e-mails sent through the list there are many solutions to your problem - some more complex than others and some more expensive than others. The solution we chose provides a system that is not tied to any particular SCADA technology, is flexible and "fairly" simple to produce once the web mechanisms became more understood.

Starting point - Active Server, HTML books and MSDN - the info is out there.

Good luck.

Jeff Dunn
[email protected]
www.its-ltd.co.uk
Industrial Technology Systems Ltd (ITS)
Tel: +44 1925 818161
Fax: +44 1925 818171