Modem: 8 bits/character and Even or Odd parity
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Thread: Modem: 8 bits/character and Even or Odd parity

  1. #1
    Join Date
    Nov 2000

    Modem: 8 bits/character and Even or Odd parity


    The serial number of my modem (56k ZOOM/FAX MODEM EXTERNAL)


    Iīm sending commands to the modem via a particular software.
    When I configure the serial port of the PC at 9600,Even parity,7 bits and 1 bit of stop the modem sends me a "0" as responses of the commands.
    If I configure the serial port as (9600,None,8,1) there is no problem too.
    When I configure the serial port as (9600, Odd, 8, 1) if I send the command ATL0 to the modem it respondes me with a "?B".
    And when I configure the serial port of the PC as (9600,Even,8,1) if I send a command to the modem it doesnīt respond nothing, and it doesnīt make the action indicated by the command. Iīve tried with the HyperTerminal of Windows and with this configuration it doesnīt work well, but with the others thereīs no problem.

    1 - Is it necessary to configure the modem in a special way in order to work with 9600 bps, Even or Odd parity, 8 bits/character, 1 bit of stop.?
    2- The modem takes this information of the serial port, doesnīt it ?
    3- Why the others configuration works well and only the especificated two fails down ?

    Thanks and Regards



  2. #2
    Join Date
    Nov 2000
    Commerce, Texas, USA
    Hey jorge,

    First. I am far from being well versed with that issue, just have been utilizing the i-net for +10 years & throughout that time have read numerous posts from others about ZOOM modems & subsequent replies from other who do know. Me try to learn. :-)

    Zoom modem are extremely fickle modems. So, I would suspect that since 8-N-1 is the setup required by the greatest majority of modem users, the software writers most likely focused on ensuring that setup functioned properly. It's been quite some time since I've seen a connection that required anything other. CompuServe ini used 7-E-1, but even they saw that they were in a minority & changed.
    I would try to find the site that provides their drivers & hope for the best.
    Anyway, after reading about endless problems with ZOOM modems, I ldecided to avoid any modem whose name begins with a "Z." :-) Not exactly scientific, but..
    Another idea. Is there an option that will enable you to force the modem to connect at a certain speed? The code that enables 56K is pretty tight, so combine that with the fickleness of Zoom modems & the "gate for failing" due to an error is widened. Forcing the modem to bypass the drivers for 56K *might* be of help. Hey, without a force range/speed, it will access those drivers eventhough they won't ultimately be utilized.

    Sorry couldn't offer more than opinions & guesses. Have a good day!

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