Good quality cable needed

[dhouston]

Dave,
Your suggested cable seems robust enough.
I only have one question: can one of the twisted pair be used for power transfer to the slave unit? I was told that the data wires should be twisted and power wires should be normal.

I've never seen a requirement that the power pair be non-twisted and doubt that twisted pair would cause a problem.

I found it merely by searching Bing using 'rs485 cable power shield waterproof' so your questions would best be addressed to the supplier.

Since you only need half-duplex, this should cost a bit less.
http://www.hyperline.com/catalog/cab...sf2-a-pe.shtml