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alqasim
Joined: 05 May 2005
Posts: 33
Helped: 4
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 17 Aug 2008 16:22 12 pin data cable |
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i have two cables , How can i know what are the losses for each? , which is better ?
And what is the maximum length that these cables can support?
Last edited by alqasim on 18 Aug 2008 6:25; edited 1 time in total |
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FvM
Joined: 22 Jan 2008
Posts: 2635
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Location: Bochum, Germany
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| 17 Aug 2008 18:32 Re: 12 pin data cable |
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This can't be determined without knowing the mode of operation (single-ended/differential) and the signal frequency range.
The LiYCY (TP) has two basic advantages compared to the LiYY: Shielding and twisted pairs. The twisted pair construction results in a defined differential impedance (around 120 ohm) and promises to limit cross talk to a tolerable range.
Loss specifications of twisted pair cables are also given by some cable manufaturers, I think.
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alqasim
Joined: 05 May 2005
Posts: 33
Helped: 4
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| 24 Aug 2008 15:57 Re: 12 pin data cable |
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attached Mr. FvM , you will find the application that this cable is used for .
can you guide me how to decide the cable.
Best Regards
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FvM
Joined: 22 Jan 2008
Posts: 2635
Helped: 431
Location: Bochum, Germany
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| 24 Aug 2008 16:20 12 pin data cable |
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| The device is using slow (9600 baud) RS422, it would probably work with the LiYY cable, but the twisted pair, screened LiYCYtp is more reliable. With termination resistors at the receiver, the serial data transmission can work for several km length, if necessary. The GPS timing pulse output would suffer from some additional uncertainty with a long cable (if it is used in the application).
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alqasim
Joined: 05 May 2005
Posts: 33
Helped: 4
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| 24 Aug 2008 17:49 Re: 12 pin data cable |
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can you Mr. FvM decide what are the missing informations that we need to know to decide what is the maximum tall that this cable can support.
other thing, i want from you to explain what you said last time
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| This can't be determined without knowing the mode of operation (single-ended/differential) |
and what is the mode for RS-422
best regard
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FvM
Joined: 22 Jan 2008
Posts: 2635
Helped: 431
Location: Bochum, Germany
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| 24 Aug 2008 19:02 12 pin data cable |
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RS 422 is differential and can be transmitted over twisted pair without extensive crosstalk. I'm no GPS expert (I just have been displaying NEMA code from a GARMIN handheld, once). I didn't yet understand, if you want to transmit the serial data stream only or also use the PPS output and which timing resolution you intend. Which cable length will be needed in your application at maximum?
P.S.: From the Acutime datasheet I understand, that the supplied interface cable is basically similar to your shielded twisted pair. If the power supply is through the interface cable, the DC resistance respectively the wire gauge also matters.
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alqasim
Joined: 05 May 2005
Posts: 33
Helped: 4
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| 08 Sep 2008 16:50 Re: 12 pin data cable |
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What i understood - from the discussion above - is the following:
to choose data cable we have to take in the consideration:
1- mode of operation (differential or single mode- cross talk )
2- If the power supply is through the interface cable (e.g PoE - wire gauge & DC resistance)
3- the baud rate. (ISI - bandwidth )
are these points enough to decide wich cable that we can use or there is more
about your question : the data that is sent through this cable is data stream , as noticed from attached data sheet.
the length that i used was 130 m and it was working fine but i want to know what is the maximum.
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