31073Re: [midatlanticretro] Re: CP/M CBIOS LST question
- Jun 1, 2013Dave McGuire <Mcguire@...> writes:
>On 06/01/2013 09:17 AM, joshbensadon wrote:Wow. Apparently, one can still buy the breakout box model I have had for
>> I save a lot of time with RS-232 by using an LED Tester. It has male
>> & female DB connectors and plugs in line to show which lines are
>> being driven. Connect it to one side first and observe the TX led is
>> on, then unplug and connect to the other side and observe the RX led
>> is on. If both show TX (or RX) led's on, then you need a NULL (or
>> undo a NULL?).
>> I highly recommend you get an 18 LED tester. There are some 9 LED
>> testers that use bi-colour LED's. These suck as you can't see the
>> data pulses unless you have a very keen eye for colour changes (which
>> I don't).
> I'm sorry but I have to disagree here. 99% of RS232 troubleshooting
>involves looking at the static states of signals, not looking for fast
>transitions due to character transfer on the TxD and RxD lines. As long
>as one end is driving TxD and the other end is driving RxD, your data
>lines will be fine. (wiring-wise)
> That said, though, if a different one works better for you, more power
>to you. But my own opinion is that the nine-LED ones are far from
>useless; in fact they're all I use anymore.
> Either way, though, something to indicate the states of the lines is
>indispensable for RS232 interfacing. They're so cheap and so necessary
>that there's really no excuse for not having one.
probably 2 decades or more:
It HAS BEEN indispensable over the years!
VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)ORG
Well I speak to machines with the voice of humanity.
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