Using the Philips P82B715 I2C extender on long cables.
(Read first AN444.pdf).

P82B715 I²C bus extender:
http://www.semiconductors.philips.co...P82B715PN.html

P82B715 Datasheet:
http://www.semiconductors.philips.co.../P82B715_6.pdf

P82B715 Application Note:
http://www.semiconductors.philips.co...otes/AN444.pdf

One mile long I2C communication using the P82B715:
http://www.semiconductors.philips.co...otes/AN452.pdf


Where to buy in small quantities:

http://www.distrelec.com Art.No: 649003
http://www.schuricht.de Art.No: 649003