Shop OBEX P1 Docs P2 Docs Learn Events
distance between the RFID Module and the Basic Stamp. — Parallax Forums

distance between the RFID Module and the Basic Stamp.

GotenGoten Posts: 70
edited 2006-09-10 20:53 in BASIC Stamp
Hello Everyone.

I'm working on RF Access Control, but i have a litle doubt, Which is the maximum distance between the RFID Module and the Basic Stamp.



RFID Module =========================== BasicStamp
·································· 50m


excuse if it is a very simple doubt.




▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

Best Regards from Chile
Goten
www.chilebot.cl




·

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-25 17:04
    Hello,

    ·· There is no fixed number of inches or feet...It really depends on a lot of conditions.· But for anything over 6" you need to start taking EMI/RFI into account.· After a couple of feet you need to consider line driving.· In thta case you should probably switch to RS-232 or RS-485/422 to get the signals the distance they need to go.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • GotenGoten Posts: 70
    edited 2006-08-25 18:25
    Thanks for answer Chris.

    It seems that i have·a big trouble... there's 50 meters from the rfid reader to the basic stamp... as you said i'll have to use RS232, but... it really works? or i should use some repeaters or something like that?shocked.gif


    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

    Best Regards from Chile
    Goten
    www.chilebot.cl




    ·
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-25 20:25
    It sounds like you'll need RS-485...I would have to recheck the specification but I think 50 Meters is a little too much for RS-232.· There are RS-485 chips available which you could use.· Dr. Tracy Allen·helped in·such a thread listed below.· You might want to peruse that for some information on RS-485.· Take care.

    http://forums.parallax.com/showthread.php?p=602070

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-08-26 11:40
    RS-232 may work at 50 meters, but very, very slowly.
    You might have to go to something like 300 baud.

    If you already have 50 meters of wire and RS-232 coming from the RFID, why not try it?

    Full-duplex RS-232 can be duplicated with two twisted pairs and RS-422 transmiter and reciever pairs.
    Half-duplex RS-232 [noparse][[/noparse]where you have to wait for the other device to stop transmission] can use the RS-485 drivers.

    In the beginning, I thought the half-duplex was okay, but you have to include software to make devices wait.
    So IMO, I think the full duplex is easily worth the extra pair of wires -- you can use PBasic's SERIAL IN and SERIAL OUT without any extra hassle. It is just like DEBUG on your computer [noparse][[/noparse]the keyboard doesn't have to wait for the screen and vise-versa].

    RS-422 and RS-485 is just much nicer for distances. Dr. Allen has used then in a lot of hostile enviroments with very very precise environmental data colllection.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "If you want more fiber, eat the package.· Not enough?· Eat the manual."········
    ···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

    Post Edited (Kramer) : 8/26/2006 12:00:38 PM GMT
  • GotenGoten Posts: 70
    edited 2006-09-10 20:53
    well...

    i'm just posting to say Thanks.

    As kramer said, and for general info, RS232 works really good at 35 mt!, and also the Rfid Module.



    Thanksburger.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

    Best Regards from Chile
    Goten
    www.chilebot.cl




    ·
Sign In or Register to comment.