Re: [LAD] [semi-OT] midi snakes using CAT5?

From: Dan Mills <dmills@email-addr-hidden>
Date: Sun Nov 01 2009 - 19:55:44 EET

On Sun, 2009-11-01 at 12:56 -0400, Raymond Martin wrote:
>
> 15 meters is a recommendation based on typical cables used in a simple system.
> Data corruption ensues somewhere after 15m, depending on cable quality, EMI,
> and so forth. I would imagine a CAT5 as having better shielding and IIRC runs
> for that are advised to somewhere up to 50m. Different frequency ranges though,
> so signal loss/degradation per meter may vary.

My recollection is that when MIDI was originally standardised, they
needed to specify a maximum length, and that 15M was chosen somewhat
arbitrarily (No tests were done, no eye patterns examined).

Now midi is actually at heart a 5mA current loop interface running at a
fairly low baud rate (31.25 Kbaud IIRC), so should be good for far more
then 15m without any problem, however nobody really knows and it will
depend a bit on the environment and the receiver.

Interference is unlikely to be an issue assuming good quality twisted
pair cable (Cat 5 counts), but bulk capacitance just might ultimately
limit the length.

Regards, Dan.

_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev@email-addr-hidden
http://lists.linuxaudio.org/mailman/listinfo/linux-audio-dev
Received on Sun Nov 1 20:15:06 2009

This archive was generated by hypermail 2.1.8 : Sun Nov 01 2009 - 20:15:06 EET