[mdlug] Semi-OT: Serial modem behavior

[Jay Nugent]

Greetings,

On Tue, 29 Jul 2014, Ingles, Raymond wrote:

>> From: Ingles, Raymond
>>> From: Bob
>>> Are there any dip switches?
>
>> Nope, not externally. One of them might be openable, but I haven't 
>> pressed it. I'll try to experiment with flow control tonight.
>
> Software flow control didn't do jack. I also tried some ATI[0-7] 
> commands, which are supposed to return a fair amount of data (and do, on 
> the Sportster). The lights blink but I just don't get anything in the 
> terminal.
>
> I fear there's some kind of electrical issue. On one of the non-working 
> modems, I'm not positive I have the right power supply. On the other - 
> the one that actually blinks its lights - It's the original wall wart. 
> But something may have failed internally.

    Is the serial port and/or cable you are using working correctly?  It 
appears that nothing on the receive side (modem toward computer) is ever 
being received.  Is there an open wire in the cable?  Does the serial port 
receive pin work?

    Might be worth tying TXD and RXD together and typing a few characters 
to verify that the cable and port actually work.  Hard to belive that BOTH 
of your modems fail to ever transmit any response codes to you.

    Good luck!
       --- Jay

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