smart transmitter output.

http://en.wikipedia.org/wiki/Hart_Protocol

i think out put of smart transmitter is 4-20 ma.in some cases we use 1-5 v dc and 1-10v dc.

Hard to say exactly what is meant by digital output, ecspecially with a transmitter. Many customers lately are asking for frequency output to better adapt to their control boards. Never really did one for current output, only for voltage outputs, but it could mean that or it might just be a sales gimmick. As far as a "smart transmitter", we had been developing smart sensors for the automotive industry but it never really took off. They have small micro controllers added to them to allow communication between individual sensors, like a ring network or CAN, instead of having to go through a central location. It was being developed to reduce the size of wire harnesses going to the ECU, as well as minimizing heat, but I believe the industry solved the issues in different ways.