Is the world ready for TTL RS-232 serial?


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  1. #1
    Join Date
    Feb 2004
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    ...In this approach all devices had to actively pass the signal regardless of whether or not they were the intended target.
    I guess there are about a bazillion ways of doing it.
    I wouldn't like this solution, because if one device on the bus fails all others further down the line would be disconnected.

    Sure, there are many ways...

    I don't know why you dislike RS485 that much, it is proven to be reliable.

    And of course you can setup a bus using a kind of RS232,
    but if it is off specs don't call it RS232,
    because RS232 implies it is within the RS232 specs.
    (And people may tend to hook it up to standard RS232 devices, which may cause problems)

    Imagine you connect a standard driver (that drives the line to +/- 12V in idle state) to "your" kind of bus . . .

    If you call it John'sSerialBus
    noone would hook it up to a standard serial port without having had a look at the Manual first (hopefully).
    regards

    Ralph

    _______________________________________________
    There are only 10 types of people:
    Those who understand binary, and those who don't ...
    _______________________________________________



  2. #2
    hansknec's Avatar
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    Quote Originally Posted by NavMicroSystems
    I wouldn't like this solution, because if one device on the bus fails all others further down the line would be disconnected.
    I agree.
    Quote Originally Posted by NavMicroSystems
    Imagine you connect a standard driver (that drives the line to +/- 12V in idle state) to "your" kind of bus . . .
    I Agree.
    I thought it would be clearly apparent that the user could only connect my devices because the 9-pin serial gets converted to RJ-11 and would only be able to plug into my network. Each device on my network has two RJ-11 sockets that allows the units to be daisy chained on to the network (in parallel).

    My existing devices are RS-485 now and they work, but I was just trying to come up with a simple to integrate RS-232 solution to save the end user some $$.
    -John

  3. #3
    hansknec's Avatar
    hansknec Guest

    Default Multidrop RS-232 Tranceiver

    http://pdfserv.maxim-ic.com/en/an/AN723.pdf

    A detailed tutorial about this very discussion. I wish I had googled "multidrop RS-232" before posing the question, but instead I had googled "multiple RS-232 devices on a single network", which got me nowhere.

    So the end answer is that there are specific RS-232 Tranceivers designed just for the very purpose of developing a multi-drop RS-232 system (that remains within the EIA-232 standard)

    The MAX3322E is one chip designed for this purpose. ($3 each)

    Thanks for your input Bruce. I will now have to weigh all my options and perhaps order a dozen of these chips to build a prototype network.

    -John

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