[query]wireless serial data modem

What's your level of electronics expertise? How much are you willing to pay? I've seen $1000 data loggers that can do this, and I've seen cheap components that can be put together to do it, but I can't manage to find any reasonably priced combos.

"dinakar31" hath wroth:

That would be RS-232

Why? 802.11b is nothing more than encapsulated ethernet 802.3 packets. Anything that talks ethernet will work over 802.11b. However, RS-232 is not ethernet and requires additional conversions to make it work. Better for a proprietary protocol that does RS-232 and forget about 802.11b or whatever.

Antenna mounting devices are usually included with the antenna. What type of "support" were you thinking?

What are you requirements? (Numbers, not descriptions).

Do you have any numbers in mind? Perhaps some clue as to the thruput requirements, range, AC/DC power, and such would also be helpful. Most of the 900MHz serial links cannot do faster than 115kbits/sec thruput.

While you're getting your numbers together, look at the various 900MHz products from:

(ethernet only) anything else that Google returns for "RS-232 wireless modem". There are quite a few. Do you need point-to-multipoint? Freewave will do that.

900MHz external yagi antennas are fairly common. Do you have an existing datalogger? Any particular make and model?

Look at this product. I use a lot of there devices and have found them to be very reliable and work very well.

NPort W2250/2150

2-port and 1-port Wireless Serial Device Servers

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Features Datasheet (PDF) Specifications Documentation & Drivers Serial-to-Wireless Flash Demo NEW! Ordering Information

Link any serial device to a Wi-Fi 802.11b network 2 or 1 RS-232/422/485 ports, at up to 230.4 Kbps

Introduction

The NPort W2250/2150 Wireless Serial Device Server extends wireless networking capabilities to printers, scales, medical equipment, manufacturing machinery, bar code readers, card readers, point-of-sale equipment and other data collection devices. NPort W2250/2150's RS-232/422/485 3-in-1 serial interface is suitable for use with most serial devices. Link up to 2/1 serial devices to your wireless network via one NPort Server IP address. More info >>

I am a software engineer and I have an embedded electronics engineer in my team. We are looking for devices as cheap as possible, may be less than $20 but can go upto $30 to $40. Can u suggest me some cheap components that can be 'put together' in reasonable amount of time ?

I think I did not explain clearly. I'll put again. My communication medium is wireless at 2.4GHz (wifi/802.11b standard) & in a range of

120 - 150 meters. I want this complete thing cheaper. So, using a micro-controller I want to send data to a device and the device should be able to convert this and should be outputting wireless data confirming to 802.11b stds. At the receiver side, I can go for a slightly costly device. As u have said, getting software for conversions would be costly.

By support, i just mean that I would be able to connect an antenna to the device. Also, I'm looking for the device to be powered by DC.

By requirements, I mean the 1), 2), 3) points mentioned in 'start of this topic'. I don't need any DHCP, web servers or any other functionality in the device(as it increases the cost). I just want the device to transmit the data(obtained thru serial interface) wirelessly. Data rate of device is also not of a concern.

"dinakar31" hath wroth:

OK. Those are the only numbers I've seen other than the SPI/Serial interface and the $20-$40 cost per end.

There are kits that can do what you want sold for OEM development. For example:

(nifty stuff) few of these are 802.11b compatible or will meet your cost objective in small quantities. Why do you need 802.11b compatibility? You're just sending serial data, not ethernet.

Speaking of serial data, is it bi-directional or do you just need to stream bits to the data logger? If so, then the unidirectional (simplex) radio is MUCH simpler and cheaper (if you dump the 802.11b requirement).

The level of intergration is not terribly clear. Do you need chips to intergrate into a design or a complete module ready to plug and play?

You'll find that data rate and range mutually affect each other. You can easily do 150 meters at 2.4Ghz, but only at fairly slow data rates or with a big directional antenna. Similarly, you can obtain MHz data rates, but not over a very large distance.

I would be tempted to suggest you look into using the common MiniPCI wireless cards, which will certainly be under $40 and are 802.11b compliant. However, interfacing your contrivance with a PCI bus may not be possible. 2nd best might be to just purchase a USB 2.4GHz dongle and deal with the interface issues. The problem there is software as much of the MAC layer is implimented in the off chip processor (driver).

I dunno. Good luck.

Hey Jeff, I'm confused by your confusion :-)

He's got an 802.11 infrastructure, and he doesn't have wires running from the serial device to the PC - so if his device could encapsulate that data in ethernet packets, any other device on the network would be able to receive them.

How do you send serial data wirelessly without using _some_ sort of wireless protocol?

It's not clear that it's truly RS-232 serial data, or some kind of SPI or other clocked serialized data link. If it's truly RS-232, he could probably use an Ethernet RS232 port (Google for "rs232 ethernet" gets some hits, for instance) and a client-mode AP.

You might need some protocol, but it wouldn't nessesarily be 802.11

You could use a CW transmitter, and a crystal detector with no protocol if you just wanted _those_ bits over _here_...

The Sychip WLAN6100EB is probably a bit overboard for you (as it also supports 802.11g), but it does support a SPI interface, 802.11b, and can be used with any antenna you choose to solder to it. It is only a module and not a system, so you'll have a lot of details to figure out on your own. Good Luck!

think you nailed it perfectly with this module in spi-slave mode. Any other solution will require some sort of sync to async hardware.

Jeff Liebermann wrote:

Definitely. If he can find the device he needs with just ethernet, adding wireless is trivial.

Sure, but he has an 802.11 infrastructure, it makes sense to use it - unless the dedicated system could be done cheaper.