Thu Aug 18 00:57:33 EDT 2016

current loops vs. rs485

Can't find a very good comparison, but the main reason current loops
are not used a lot is because they consume a lot of power.

For sparse communication with idle=off this doesn't matter.

Now for RS485, apparently RTS is supposed to be used as an enable signal.

FTDI chips have a direction pin.  Or use a monostable trigger on the
TX start bit.

EDIT: disadvantage of current loop is that it's single duplex (or
needs transformer coupling).