Shop OBEX P1 Docs P2 Docs Learn Events
pc serial port connection — Parallax Forums

pc serial port connection

rrrr Posts: 63
edited 2006-02-13 23:07 in BASIC Stamp
I·am working on a project that requires my stamp to be mounted about 20 feet high. However,·I want to be able to program the stamp from the ground. Is there limitations on the length of wire that can be used to connect to my serial port? Also, is there a certain kind of wire i should be using?

thanks for your help...

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-02-13 08:12
    rr -

    I'm sure there is a practical limitation on the length, but I wouldn't think that 20 feet would be a problem. I'd use random lay, twisted pair cable, like telephone station cable.

    Will this be an indoor or outdoor application? If it's indoors, will there be any fluorescent fixtures nearby?

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
  • GearHeadGearHead Posts: 23
    edited 2006-02-13 08:38
    This should help.

    Wiring length
    The length of the cable also plays a part in maximum speed. The longer the cable, the greater the cable's capacitance and the slower the speed at which you can obtain accurate results. A large capacitance means voltage changes on one signal wire may be transmitted to an adjacent signal wire. Fifty feet is commonly quoted as the maximum distance, but this is not specified in the standard. It is generally recommend a maximum distance of 50 meters, but this depends on the type of hardware you are connecting and characteristics of the cable.

    Maximum length of cables
    Baud rate [noparse][[/noparse]Bd] Max length [noparse][[/noparse]ft] Max length [noparse][[/noparse]m]
    19200 50 15
    9600 500 150
    4800 1000 300
    2400 3000 900
  • allanlane5allanlane5 Posts: 3,815
    edited 2006-02-13 14:11
    Also, be aware that the BS2 programs at 9600 baud (I believe).

    500 feet sounds like a really long cable for 9600 baud -- but probably 100 to 150 feet would work fine, so your 20' rise would not be a problem at all.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-02-13 15:10
    rr,

    How much electrical noise from other equipment is in the area? This may or may not be a concern. Tying a 1K resistor between ATN (pin 3) and VSS (pin 4 or pin 23)
    can sometimes help noisy environments where the programming cable remains connected to the BS2.

    I have used about 75ft of standard "flat-grey" telephone cable without much problem with the configuration mentioned above.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • rrrr Posts: 63
    edited 2006-02-13 20:48
    there will be neon lights close as well as flourescent lights. would it help to use shielded wire???
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-02-13 23:07
    rr -

    Definitely use shielded cable!

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
Sign In or Register to comment.