Subject:
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Re: Re[2]: phone cord length
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 7 Mar 1997 02:29:05 GMT
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Original-From:
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Alan Matthews <alanm@sprynet.com^AntiSpam^>
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Viewed:
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1767 times
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Sorry Fred, but I must respectfully disagree.....
Fred G. Martin wrote:
(snip)
>
> BTW, while we're on the topic of serial and phone cords, please be
> VERY CAREFUL when swapping phone cords. The Handy Board requires a
> telephone-style cord. Many of us have network-style RJ11 cords lying
> around our offices, which have a half twist in their wiring.
Actually it is phone cords which are the crossover type. Use of a patch-
cord tester confirms this. I am not familiar with any RJ11 network cables,
but I know that the standard line cord for a phone is a crossover cable.
>
> Network-style RJ11 cables CANNOT, SHOULD NOT, and BETTER NOT be used
> with Handy Boards.
This is still true, since the effect of using the wrong one is the same.
>
> If you use a network style cable, you invert the power and ground
> connections, which blows up the 47 ohm charge resistor on your serial
> interface board, along with potential for greater damage.
>
> Here is how you tell if you have a telephone-style or network-style
> RJ11 cable. (snip)
You actually need to put the RJ11 plugs side by side, so they are oriented
the same way, to see whether they are straight through or crossover. This
way you see wire color for pin 1 on each end and pin 2, pin 3, etc.
+-----------+ \
-----------------|black ====| Pin 1 \
|red ====| Pin 2 \
|green ====| Pin 3 \
-----------------|yellow ====| Pin 4 \
+-----------+ \
----- straight-through cable
+-----------+ /
-----------------|black ====| Pin 1 /
|red ====| Pin 2 /
|green ====| Pin 3 /
-----------------|yellow ====| Pin 4 /
+-----------+ /
+-----------+ \
-----------------|black ====| Pin 1 \
|red ====| Pin 2 \
|green ====| Pin 3 \
-----------------|yellow ====| Pin 4 \
+-----------+ \
----- cross-over (phone) cable
+-----------+ /
-----------------|yellow ====| Pin 1 /
|green ====| Pin 2 /
|red ====| Pin 3 /
-----------------|black ====| Pin 4 /
+-----------+ /
Best regards,
Alan
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Message has 1 Reply:
 | | Re: Re[2]: phone cord length
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| thx for correcting my wording. e.g., instead of saying "half twist" i should say "straight through". anyhow, we agree on the definition of what is a phone cable and what is not a phone cable, we just have a different way of illustrating it. the (...) (28 years ago, 7-Mar-97, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: Re[2]: phone cord length
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| (...) No, that is wrong; the RS232 is converted to TTL at the serial interface board, so you do have TTL on the phone cord. In any event, I would guess that 50 ft. would not be a problem; we're talking about 9600 baud here which is pretty slow. BTW, (...) (28 years ago, 4-Mar-97, to lugnet.robotics.handyboard)
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