Building Management Web based or? 2

[Newnorthman]

We are looking at a building a new school in a rural area which has telepone line which is able to provide only a internet access with modem speed limited to 33.6Kbs. No high speed via telephone or cable. We were considering web-based software for the building control, but now can anyone tell me if we can use this dsoftware with the 33kbs connection.

thanks

 

[automationprogrammer]

Are you planning to have a web server at the school to publish web pages to the Internet? If so how do you plan to connect the server to the Internet? Using a dial up line to an ISP may be a problem as you will need a static IP address for the server.

Or are you planning to have users call into the modem at the school when they want access to the web server pages? I have done that over a dial up line. Performance is slow but gets the job done.

 

[automatic2]

No reason why not, even high speed packets run into bottlenecks. Typically environment control software is only transmitting report data and configuration data. The actual control is performed onsite, so transmission delays will only mean you need to wait a extra minute for status reports, emeregency callouts, or setpoint/configuration writes. Your packaged system supplier will tell you your hardware configuration.

 

[automationprogrammer]

I am working on a similar applications for a pumping station. At the station we have a PLC connected to a local CIMPLICITY HMI SCADA package from GE Fanuc. CIMPLICITY can act as a web server. Currently this is up and running, it serves web pages to any PC connected to the local LAN.

In the next phase of this project we want to provide remote access for the plant operators. Currently we use PC Anywhere to allow them to dial into the HMI PC and view its screens. We would like to change this so that the operators could access the screens via the Internet. The problem I have (like you) is that the site is in a rural area. We are trying to find a cost effective way to connect the server to the Internet 24x7x365.

I have looked into dial up, cable modem, and DSL connections from the local phone company, cable, and ISP companies. The dial up is fine for dialing into the site but I don't think it will work for the web server at the site. Usually dial up doesn't provide a static IP address and my guess is dial up would not be reliable enough. Cable broadband is not offered in the area. That leaves DSL with a static IP address. This would work great but will cost about $90/month, a bit much to serve one web page showing the status of a couple of pumps.

What I am looking for is a cheap way to get my status info out of the plant and onto the web. Is there another less expensive way to connect a web server to the Internet, even if the bandwidth is limited? High speed performance is not a big issue, we just need 24x7 access.

Or is there some other way to get this info onto the net?

 

[johnwm]

Looks like you need dynamic DNS - enables you to have a domain name lookup which will track the IP address that you currently have. Try :

http://www.dyndns.org/services/dns/dyndns/

Good Luck
johnwm
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[quark]

What permissions do you provide for web based access? The main drawback, even with multiple access installations on LAN, is virus. The BMS guys offer you rocket science to get the orders but they keep on warning you about multiple access. You be specific with this issue right from the beginning. My idea is to keep it simple.

Regards,

 

[automationprogrammer]

I am really a novice when it comes to the security side of the system. My thought is that I will arrange for a DSL connection to the plant. Then add a hardware router/firewall for one layer of security. I'll then add a software firewall and anti-virus protection on the server. On both firewalls I will lockdown all ports except those needed by the web server (80, etc). I'll also make sure that all user names needed to log onto the server have strong passwords. Other than that I don't know what to do.

I also still need to find an inexpensive alternative to DSL. johnwm suggested dynamic DNS to allow me to associate a domain name with a changing IP address. This would allow me to use a dial up connection from the server to the web and still host a web page that users could find. However I am not sure if I can configure the web server to dial and maintain a full time connection over a dial up link or if the performance will be acceptable (33k baud is about the best I can get at this location).

Thanks for any suggestions!

PS Who or what is BMS? Building Management System??

 

[richs]

Hi-

You might also want to look into https protocols and the like. The data is encrypted in the transmission. This is commonly used when doing web based credit card shopping.

Depending upon your server application program and your OS there are various levels of security that can be passed to it. I cannot answer for Windoze, nor any http server other than Apache, but for Linux and Apache, turning on sessions control and secure transmissions, might prove to be adequate for those not wishing very hot or very cold buildings or pumping into or out of unexpected situations.

One easy to implement "trick" is to have the http server "listen" on a non-standard 80 or 8080 port number. This will NOT help with the determined attacker but will help with the casual ones. But, it cuts down on the rif-raf and is easy to implement.

When dealing with slow transmissions, you might want to consider a Java applet for the communications. I'm not a big fan of Java, but passing along large amounts of data can be reduced by proper construction of the data packets between the server and client. This is when you want to have icons in the pages, and have them manipulated on the web page. Simple text and forms is another option, allbeit not as "pretty". If you have a limited set of icons you might get away with preloading them via Javascript and using those images. Another "trick" is to use "tables"
with different background colors and different widths of
the fields. This can generate a very quick horizontal bar graph without sending an icon (picture) at all. Very little overhead.

Please also note the terms and conditions of whatever DSL
service is available. I know in my area, SBC does NOT
allow one to host a web server. I had to go to a smaller
third party provider that uses SBC equipment to obtain
a lower cost option. Errrr, I should say that SBC did not
provide a "non-business" DSL connection. They do offer one
for significantly more $ per month.

I think that you can easily implement a dynamic DHCP
(unknown IP address) via some free services. One of the links that I have (that I HAVE NOT RESEARCHED NOR USED) is:

http://www.dyndns.org/

Again, I haven't used the service so I cannot comment on it.

You may or may not still want to select a domain name and registrar for your application. It is not necessarily a requirement. I am assuming that your audience is very limited (hopefully) and that you can get away with something like:

https://192.168.1.1:8048/index.php

for getting to your pages. Heh, heh, the 192.168.1.1 is not a very valid number to use. It's a level C address that is commonly used for local access..... but you get
the idea.

Please keep us posted. I personally am very interetested in dynamic web insturmentation, and would like to hear of your progress.


Finally, for the rural pumping station. Might I suggest that you get your company to pay for DSL at your house, then have the server do a PPP to the pumping station. Having the server at your house is pretty easy. I have my server on top of my freezer in the garage. It acts as my mail server, web server, DNS, firewall and NAT. If you can get the company to pay for the DSL at your house, and the cost of a cheap PC, you might (hint, hint) be able to leverage the DSL for your own uses. After all it's a fair trade for the electricity that the server is using......
Then a dedicated phone line for the PPP link.

Hope these rather unconnected thoughts help.


Cheers,

Rich S.

 

[automationprogrammer]

Thanks Rich, lots of great info in your post.

I'd like to ask more about the PPP solution. It sounds like it would require a dedicated (leased line) from the plant to the server's location which is typically pretty expensive. Is there another way to establish the PPP connection on a 24x7 bases from the plant to the server?

I currently use a dial up PPP connection from my office to the plant. This allows me to connect to the plant's LAN and get pages from the plant's webserver. We use port 80 but plan to change that if we connect to the net. PS The webserver is built into an HMI package that we need onsite, so it is essentially free so I like the option of having the server at the plant.

The server uses a Java applet to create the screens the user sees. By reducing the amount of info on the screen to the basics I have achieved reasonable performance on a 33k baud dial up line. My challenge now is to make this a full time, 24x7x365 installation so we can access the pages from the net.

 

[richs]

Hi-

Well, this is rapidly getting out of my area of expertise, however, I suppose you can "tunnel" a server from the internet to the plant server. This *COULD* be done with a POTS (plain old telephone service).

If you have a linux type system, of course you can have the clients "dial in" to the web server. You would have to supply modems to all the clients (Yuk).

Alternatively, a seperate server doing the tunneling might be in order. You have the server configured to do a dial out to the plant server, via PPP or SLIP on demand, this would dial the plant server. The plant server picks up the connection and again, spits it out to the "outside server" which translates it back to the WAN (internet). Again, you would need an outside box (as far as I know) to accomplish this. But then you are back to the outside box again, and it might be easier (read as transfers less information) between the servers if you have the outside server be the httpd server.

I just got through looking at some of the .htaccess transactions with a packet sniffer and boy, there sure is a lot of overhead passed between the client and server! Even doing the basic authorization. And the data itself wasn't even encripted, just the user and password.

Funny how things worked out. I was looking a little on the htaccess because of your post, then a friend locally has been trying to dink with it. So, I got to kill two birds with one stone.

A word on the java applets. Just for fun, while researching the htaccess thing, I ran across my old applet that I whomped up. I was using an "new" brower, and even with a fast lan/wan connection, it was somewhat irritiating to download the JRE and jar files from sun. Of course, that only happens once, but I do remember doing it with a modem and that took a *LONG* time.

In this application, it would most likely be o.k., but I can certianly see the following situation happen:

1. Bigwig boss is bragging about the web insturmentation at
the plant at a friend's house.
2. The friend only has a modem connection.
3. Boss says "no problem".
4. Loads up the page and has to spend 15-20 minutes loading
sun software.....
5. Boss'es blood pressure rises.
6. Boss has "words with you" the next day...........

In my case, replace boss with client. If it's not explicitly mentioned up front, there will be words.

Typically, I stick to PHP and Javascript. I try to keep the graphics as small as possible. In this arena, we are looking for control and information, not pretty pictures.

Best of luck with your efforts, please let us know how things work out. As I mentioned earlier, I'm quite interested in web insturmentation.

Cheers,

Rich S.