Printing to a COM port when the hardware's been removed

Posted on 2007-09-28
Last Modified: 2010-04-26
I have a solution where I attach a JADTech ( to a serial port, then read the transmissions from the JADTech via an Ethernet cable.

My question is whether there is any danger to the system if the "black box" is removed, and there's nothing there to catch the data.

Does it simply vanish?  Does it put the system in danger in any way?  It's Windows 2000.

Question by:newbieweb
    LVL 44

    Expert Comment

    Your link doesn't work.

    In general, neither serial nor ethernet is likely to damage a computer or system on the other end that is not responding to the serial or ethernet requests.  If there is no serial or RJ-45 acknowledgement, the packets simply get LOST, and nothing happens to them at the computer that is ignoring the packets.

    Unless JADTech is doing something that violates the serial and ethernet protocols, there would be no danger in having one device transmitting, but the other recipient system just ignoring the data packets.

    Author Comment

    try this:

    What I mean is can some queue overflow, for example, on the machine which is doing the writing to the COM port, that could cause some problem? Since I won't have the JADTech always plugged in, the receiving machine is not my concern.

    LVL 44

    Accepted Solution

    "can some queue overflow"

    queue overflows all the time on COM ports (and ethernet) -- that is what the packet checksum is for, to see that the queue didn't overflow.

    "that could cause some problem"

    not with serial or ethernet, both protocols are designed to resend packets if incomplete or lost.

    Call them -- (310) 212-0600 -- to confirm this, it is standard for these protocols.  Good luck.

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