RFID Project, brilliant minds needed =)

gth629e

Hello all,

I am current;y working on an inventory tracking type system, that incorporates LF RFID tags. I would like to use the parallax RFID reader to read the tags and then "send" that to my computer. I realize that the RFID reader outputs a TTL level signal that could be harmful to my pc, so..

Question 1:

Instead of making my own circuit with a MAX232 line driver, could I use this TTL to RS232 converter?

microcontrollershop.com/product_info.php?currency=USD&products_id=2154

Question 2:

I would use the USB model, however, in the future this will be a wireless system and I can't seem to find any way to do long range usb wireless communication. There are several solutions for wireless RS232 communication such as these.



www.cdw.com/shop/products/default.aspx?edc=1390671&cm_mmc=ShoppingFeeds-_-GoogleBase-_-NetComm%20Products-_-1390671_Black%20Box%20900-MHz%20Serial%20Transceiver%20RS-232%20%281%29%20Client/Serve_BLA-MDR292A

Do any of you know of a way to do wireless usb over long range 2000 ft +? Cause if I could use USB I would use an RFID wedge which simply emulates a keyboard.

Mike Green

1) You could use the TTL to RS232 converter whose link you gave. It's basically a preassembled MAX232 unit with connectors.

2) There are some USB to Ethernet converters and I believe these would work over a WiFi link.

gth629e

Mike,

Once again thanks for your prompt reply. I have heard some people say that you can buy a usb to rj45 converter and then use a wlan router or similar to obtain wireless usb and then I've heard some people say that doesn't work I guess I just have to give it a try. Although even if it does work I'm not sure that the usb device would still show up as an HID device, or if I could access the usb device in the same manner.

Do you foresee any problem by going from TTL to RS232 to wireless RS232 back to the computer? Also, I have found a few TTL/Rs232 RFID readers with a read range larger than the one offered by parallax. (11" - 5m). The only problem is that there is very little documentation provided with them. I'm going to the shack tomorrow to pick up the parallax model. Do you think I could use any of these readers in place of this model. I realize that the encoding may be a little different. Some examples below.

www.robotshop.us/rfid-direct-talk-application-RW-210-1.html

and also

www.futurlec.com/EM_Card_Reader.shtml

Thanks again, and I am open to any ideas for long rang RFID projects. Its all a learning experience.

Post Edited (gth629e) : 10/30/2009 3:15:13 AM GMT

Mike Green

The RobotShop RFID reader is for 13MHz tags. It is completely different (and incompatible) from the RFID reader sold by Parallax. The Parallax tags won't work with it.

The Futurlec RFID reader may or may not have any commonality with the Parallax reader and tags. There's insufficient information provided by Futurlec to tell.

Lantronix has USB to Ethernet adapters (www.lantronix.com/device-networking/external-device-servers/ubox.html). These should be able to work with wireless Ethernet links.

For just the RFID, I suspect an RS232 wireless link would be best, particularly since you just need a half duplex line with a transmitter on the RFID end and a receiver on the PC end.

gth629e

Mike,

Thanks for the input and the link. I agree, hardware wise the rs232 would be best. It's just there would be zero programing involved for a wedge rfid type device. Yes, currently I haven't chosen to go with 13mhz or the 125khz tags and reader as of yet. I will be using the 125khz tags for prototyping but I prefer the 13mhz tags for actual use.

I'll check out that print server and try and find some information about using other usb devices. I'll post my findings on here so I can use this thread as my log of sorts. Thanks for your help thus far.