any suggestions to connect trig and echo of ultrasonic to microcontroller via dc

[hitronics]

I have ultrasonic sensor has 4 pins as + & - & trig & echo then is there a way to inject echo to dc lines then need to read pulse width via 12F so want to use just two wires to connect ultrasonic sensor to 12F the length of dc lines 30 meters

[hitronics]

I am thinking to use another microcontroller with sensor side but how to connect to dc bus lines to send data to another side of main board?

[dr-zin]

If I understand correctly, you can power the unit remotely (though gnd connections from both monitor and sensor ends of the length must be joined).  Using a 5 VDC (or less) powered u-controller to send a trigger pulse down a 30 meter line will require both power amplification and timing compensation.  Using a separate PIC to trigger and receive/process the SR-04 ultrasonic signals may be workable, but sending the result back down the 30m line will still be problematic (maybe 4-20mA current loop?).  I would try sending a digital version of the result back to the monitor board using either a pulsed laser signal or a modulated radio signal.  I'm not sure if Bluetooth modules will transmit that far (may require a relay extender part way back along the way)?  An FM transmitter using PFM or other technique will probably give you the range you need without running afoul of regulatory agencies who frown on excessively powered broadcast units.  You could be extra safe by transmitting on 13.56 MHz or other ISM band which are unregulated (varies by country).  Good luck, and tell us how you make out!

[dr-zin]

Might be an expensive option, but 30 meters of fiber optic line with power LED and receiver at each end would provide isolation and a speedy path to send data back and forth to communicate signals reliably (no interference).  NOT for hobbyists, but may be an option for industrial settings.  We don't know your circumstances...

[atomix]

Current loop 4-20 ma