Satellite comms to a PLC/touch screen

[BobB 58]

Looking at a proposal at the moment and need some HELP!! Client wishes to communicate with a PLC and/or touch screen by satellite. The site(s) will be very remote. Requirement for a camera to monitor weather, intruders etc and send photos back to a central point. Communications with a weather station and other devices. Camera to be controlled locally for automatic sending of photos and a manual override from a web page to position the camera to different angles. Access to the system by way of a web browser etc. Looking at using Omron touch screens as there is a video board option available for cameras. The screen also has a web server built in. Could maybe (?) use the web page to punch through to the PLC to move the camera as required. Position detection by way of a rotary encoder perhaps. Main issue at the moment is satellite comms gear. The site (s) will be remote and powered by solar cells and batteries. Any thoughts/recommendations? Thanks for taking a look. __________________

[Ken Moore 23]

I recently installed a CCTV camera for monitoring remote waste water treatment equipment. Hard wired ethernet, but should work the same with a satellite. There are IP cameras available that already do everything you listed, have built in web servers, able to control remotely etc...., run of 12VDC. Some models work in total darkness with there on infrared LED light source, it all depends on how much your budget can stand. I would look into high end security cameras, they are costly, but may be cheaper than buying a PLC and encoder and a camera. Just google security cameras, there are LOTS of vendors.

[BobB 58]

Thanks for the response Ken. Unfortunately I have to use a PLC as there are other things to be monitored/started etc and all will have to appear on web pages. Voltage, current etc etc. It makes it hard as my client does not want to make very public the full nature of the automation of the application. They are using technology that was developed in Russia during the cold war for increasing rainfall. They use a small generator and high voltage to ionise clouds to increase rain. It is not rocket science and is proven and available but the automation is not. The things they wish to add will probably be mostly relevant to Australia and the US (California) even to monitoring busfires etc. Bit of a challenge for me - technical carrot if you will that I cannot resist. If it is of interest here is a link to their website www.australianrain.com.au Edited 15 Apr 2009 by BobB

[BobLfoot 302]

When I first read you post I thought of adding a low cost VPN box at the remote site and connecting everything at the remote site via harwire Ethernet and patching that into the VPN module which accesses the Satcom Modem. it might be worth adding a cheap 200 laptop at the remote site also.

[Steve Bailey 118]

Check out these guys and their Tbox and Tbox Lite product lines. http://www.cse-semaphore.com/default.php I'm not sure whether the satellite comms will be an issue with them, but your application sounds like what they're marketing themselves toward.

[FIA Ranch 0]

Satellite communications is an animal unto itself. First, as far as interface goes, most systems are standard ethernet. So the clients' system can be built how ever the client wishes as long as the end result is an ethenet connection to the satellite system (network). The list of issues dealing with satellite is a long one, far beyond the scope of this forum. The highlights are: 1. Latency (delay). There will be an absolute minimum of 1/2 second delay in all transmissions. Depending on a whole seperate list of factors, this delay can be upwards of 1-2 seconds. 2. Speed. Satellite speed is not syncronous. Typically the uplink from the remote site will be much lower speed than the downlink to the remote site. 3. Availability. Weather plays a big factor in satellite communications. So any mission-critical applications/services could be jeopardized by weather not only at the remote location, but also at the satellite providers NOC. 4. Cost. The capital cost of deploying satellite systems can be high, and it is not a DIY project. The recurring costs are dependant on the level of service the client wants. If they want "the world", it will cost them the world. 5. Power. Depending on the chosen system, the power requirements for a satellite system can run into the 100's of watts. So that will play a role in sizing the solar system. So tread lightly. Satellite works well as long as you stay within the bounds of it limitations and/or pay enough to minimize some of the limitations. ------------------------ My two cents and five bucks will get you a (small) Starbucks

[paulengr 44]

I would strongly suggest you talk to Hughes and perhaps Echostar. They have their own satellites (18" dish digital TV stuff). They also have a lot of additional support for commercial customers that isn't obvious when you look at their digital TV web sites. I know there are also similar vendors out there. Look for the key word "VSAT" since that's what you are going to be using. There is quite a variety among VSAT stations. The most popular is obviously one that gives you a "real" internet connection. But the underyling protocol is TDMA...each VSAT station is assigned a time slot and must transmit ONLY within it's allocated time slots. This is done for latency reasons (takes a long time for a request-to-send/okay-to-send/data/acknowledge sequence with 1/2-1 second up and down each time). There are a huge variety of these things. Some are limited to squirting out E-mail or GPS data every few seconds/minutes. Some let you carry on a full internet connection. Some let you broadcast large downloads to an internal corporate network such as sending video to a large number of consumer stores such as "Walmart". And there's probably any number of in-between combinations. Some are more "customized" in nature than others. ALL will be very touchy about installation requirements. It is generally frowned upon if you aim your tight beam microwave transmitter at the wrong satellite and interfere with someone else's communications. This is why you cannot buy "satellite internet" stations "do-it-yourself". Starband (which is a reseller of Echostar's service) did just that and some "do-it-yourself" guys apparently interfered with a couple U.S. government satellites.