Post by thread:Off Topic Ethernet Question.

Sorry for the off topic question, but someone here may know the answer to this one. What is the output on a standard Ethernet card?, the RJ45 has 4 used pins I know they are rx1 rx2, tx1 tx2, but would it be possible and I know they are 120ohms. The question is, whats stopping us from using a small rx/tx RF module and using two Ethernet cards as a wireless interface, Yes I know that your not going to get 10mb but for some stuff like terminal communications process control and other stuff its not going to matter. The idea came to me when I discovered a schematic for an inexpensive laser RS232 transceiver. In the environment IM trying to setup this control system in we are not able to use Ethernet cables or wired networks due to the machinery.. Its an EDM machine, and the RF in the room is WAY to high, the PC is in a Faraday cage because we originally had trouble with it locking up :(. Regards Andrew Hooper

Could you please tell me where to get a copy of this RS232 "laser" transceiver schematic? It sounds very interesting - I might be able to use it to finally defeat Austin Powers. <return pinky to mouth> -Randy Glenn E-Mail: spam_OUTPICxpertTakeThisOuTyahoo.com Web: http://i.am/PICxpert Currently wondering why I can't get in to Safe Mode - where's a Mac when you need it? {Original Message removed}

The question is, whats stopping us from using a small rx/tx RF module and using two Ethernet cards as a wireless interface, Yes I know that your not going to get 10mb but for some stuff like terminal communications process control and other stuff its not going to matter. Most of the wireless rx/tx modules operate at 2400 to 64000 bits per second, which is closer to your async port speed than ethernet (by quite a large margin.) Might as well just use the async ports with SLIP or PPP. They should talk ok to rx/tx modules, or to a TNC for use with longer range amateur radios. In case you hadn't noticed, 1Mbps and higher wireless "home area" networks are becoming commercialized - you can get it all for a couple hundred $$. Wireless metropolitan area nets are also available, but you'll pay monthly service fees and I don't know how much for airtime (maybe 0 for some, and others seem to be based on cellular modems at typical cellular rates.) I'm not sure what the advantage of a proprietary scheme would be... BillW

I think you answered your own question about what would keep you from using an rx/tx RF module... Andrew Hooper wrote: Q: whats stopping us from using a small rx/tx RF module A: Its an EDM machine, and the RF in the room is WAY to high However, I would suggest you use *shielded* cat5 cable (most cat5 sold is unshielded) and that you go with 10baseT (100baseT may be more susceptable to the noise in the room) Most of the home phoneline and wireless networks were made for the relatively low electrical noise of the (average ;-) home, and will likely have bad results in your intended environment. Also, you can use CAN for computer networking, which is intended for high noise environments, and is very robust with hardware error correcting etc. It can go much faster than your typical RF solution. I hope this helps! -Adam Andrew Hooper wrote: > whats stopping us from using a small rx/tx RF module > Its an EDM machine, and the RF in the room is WAY to high

www.alphalink.com.au/~derekw/upntcvr.htm Realtime Control's UPN Laser Transceiver http://home.vicnet.net.au/~upnet/ a laser based network more at: http://204.210.50.240/fiberoptics.htm Also, please use [OT] rather than Off Topic so that people who are short on time can use an automated system to filter their PICList email. --- James Newton .....jamesnewtonKILLspam@spam@geocities.com 1-619-652-0593 http://techref.homepage.com The Technical Details Site. Members can add private/public comments/pages ($0 TANSTAAFL web hosting) {Original Message removed}

Andrew Hooper wrote: > In the environment IM trying to setup this control system in we are > not able to use Ethernet cables or wired networks due to the > machinery.. Its an EDM machine, and the RF in the room is WAY to high, > the PC is in a Faraday cage because we originally had trouble with it > locking up :(. You've just told us then, that there's *no way* you could consider using an RF network of any kind or form in there. Fairly obviously, you'll need fibre optic links, so go search for those. I suspect Ethernet using 10Base-2 and fully-shielded cable and connectors would actually work as a wired option, but the fibre sounds easier to deploy. If as mentioned, you don't really need Ethernet speed or multiple branches, than plain comms speed (115,000 Baud) fibre should do. -- Cheers, Paul B.

Sorry for not being a little clearer. The Wireless connection was for another project and not for the EDM machine. I have tried shielded Cat5 but was not successful. Doh!, did not even think of using fibre, this will solve the problem :) Thanks for the help Regards Andrew Hooper {Original Message removed}