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Old September 27th, 2003, 01:42 PM   #1
djshorty
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PLC Automation over TCP/IP Ethernet

For my project, I'm looking to be able to read/write values to the PLC from the web. Avoiding use of a PC connected to the PLC is preferred.

This thread was pretty informative, but I need some clarification on certain topics.

I understand the many PLCs have 3rd party drivers for TCP/IP ethernet automation. What is the difference between these and an "OPC Server" or "RSLinx"? Can any of these be embedded into a web application? Links to other drivers would be great as well.

How does one VPN to a PLC? Is there some device that you place between the PLC and the internet drop that actually has an IP address? I'm not sure how the PLC can be assigned an IP without some external device.

I am open to suggestion for PLCs (as well as other devices) that would make this task easier. I looked for the E-Series Terminal that Steve Wood suggested in the previously mentioned thread but there was no mention of the E-View software.

Thanks guys.

Last edited by djshorty; September 27th, 2003 at 02:10 PM.
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Old September 27th, 2003, 03:55 PM   #2
The Dark Knight
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If you are familiar with a web pages, Siemens s7 plc's, and java, you can get an Ethernet Module with a built-in web/ftp server.


the module is a 343-1 IT
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Old September 28th, 2003, 01:19 AM   #3
djshorty
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The web server for the Siemens PLC is only for publishing acquired data right? Does it provide a web interface to control the PLC (write values)?
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Old September 29th, 2003, 10:09 AM   #4
glaverty
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Dj,

Here are some more posts for you to check out.

First

Second

Third

Quote:
How does one VPN to a PLC? Is there some device that you place between the PLC and the internet drop that actually has an IP address? I'm not sure how the PLC can be assigned an IP without some external device.
Ken mentions some VPN appliances in some of those posts, I'm not sure how they do it where I work I just know its set up and I can VPN into a specific IP address and it is just like plugging my laptop into the network at work only I'm doing it over the internet. Your PLC will need an IP address, one that you know, otherwise how can you connect to it?

Quote:
I understand the many PLCs have 3rd party drivers for TCP/IP ethernet automation. What is the difference between these and an "OPC Server" or "RSLinx"? Can any of these be embedded into a web application? Links to other drivers would be great as well.
I have set up and OPC Server and client but I have never published it to a web application. I would think it is possible. The biggest difference you will notice between 3rd party drivers and things like OPC and RSLinx is the price. You can usually get a driver for a few hundred bucks or so. The others will cost you in the thousands, however they have a lot of functionality already built into them, so you get what you pay for.

Like Dark Knight said you can get PLC's with Web Servers built into them that may do what you want. I have never used one but they look pretty cool.
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Old September 29th, 2003, 12:57 PM   #5
djshorty
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So when you are setting up an OPC server and client, must there be a PC on-site connected to the PLC?

Then the remote client is embedded in some application, correct?
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Old September 29th, 2003, 02:17 PM   #6
glaverty
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Well it depends on what you want to do. You could have an OPC Server running in a different location but it would need a full time connection to the PLC in order to get data from it constantly. My OPC Server is connected to 5 different PLC's getting data from all of them over the ethernet all the time. The client can be remote though in my case the client is running on the same computer as the server and writing data to an Access data base. I have a Visual Basic program that pulls specific data from the OPC Server so that I can see production numbers and the status of machines out on the floor. The VB program can be run from any computer that can connect to the OPC Server.

I don't seen any reason that your client couldn't be a web application, which is what your are looking for right?

Check out this page it has a little picture overview of OPC and a Client that you can download and try out for free.

If you want a free server to mess with check out www.kepware.com
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Old November 6th, 2003, 12:10 PM   #7
conr
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Hey,
my project is much the same,i must control a plc over the ethernet using a micro controller base with a web portal build in.Its called the ethernut board
www.ethernut.de
its very very slick the web portal is all written in c but the problem is i have little to no plc experience.My plan is to connect the plc to the serial port and control it via the web (on the micro controller).I was wondering if anyone has any ideas?Can i Programme up the plc to accept i/o using C?(the memory on the microcontroller is not so big)
any help would be well slick
Regard
Conor
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Old November 6th, 2003, 03:30 PM   #8
Allen Nelson
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In the catagory of "What a Coincidence"

Today I attended a training session involving a Modicon PLC which has an ethernet module which works as a Web server, creating a Web page with live PLC data. Data writes are also permitted, along with security access of pages.

No PC required (except to set this up, and to view the pags, of course). Check it out at Modicon.com, and look for FactoryCast under HMI/SCADA software.
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