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Echo on RS232 programming port — Parallax Forums

Echo on RS232 programming port

aletheiaaletheia Posts: 2
edited 2004-10-29 15:49 in BASIC Stamp
Please, can anyone tell me how disable the echo that a BOE sends back every time I send it a string of command.
I'll try to explain at my best: a "waitstr" command waits for a known name and then dispatches via a "select" instruction to execute it.
every time I send a character (or a string) to the BOE it seems to send back the same character (or string).
Is there any way to stop this?
Tnx inadvance for your help!
Enzo.

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-29 12:09
    You can't. The echo is caused by the design of the circuit and there is no way to prevent it. You software on the other end must filter the echoed characters.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • aletheiaaletheia Posts: 2
    edited 2004-10-29 13:10
    Tnx Jon. But can't you suggest me a workaround for this? The big trouble arises because I have more BOE each connected to a Radiotronix EWD HDTC transceiver and a receiver conencted to a PC that logs the answers from them; all they wait for a "sign" string that identifies uniquely each of them. But when I send the "sign" string to one all transmit back that string and this goes on back and forth (randomly until for some strange thing the clutter stops, more often when a character is send but not always).
    How could I stop this nightmare?
    I'm gonna demonstrate to my customer the project! Please help me!!!
    Enzo.
  • allanlane5allanlane5 Posts: 3,815
    edited 2004-10-29 13:23
    You can install a MAX232 circuit (with 4 capacitors), and use some other pins besides the programming port to talk to the Radiotronix unit.

    If the Radiotronix transciever is using TTL signalling, just connect it directly to a different pin besides the programming port.
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-29 14:13
    Yes, Allan's suggestion will work.· The hardware echo on the programming port is used by the editor to verify that a BASIC Stamp is plugged into the socket and to validate the physical connection (while programming, each echoed byte is compared to what was just sent).· It's not a nightmare, it's a feature. tongue.gif

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • AlWilliamsAWCAlWilliamsAWC Posts: 135
    edited 2004-10-29 15:24
    I was going to make the same suggestion as Allan.. see http://www.awce.com/rs1.htm for one way to add a MAX232 without too much hassle.

    Regards,

    Al Williams
    AWC
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-29 15:49
    The RS-1 is a great solution for breadboards. If you have a Parallax Boe, you could also use the Parallax RS-232 AppMod.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
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