I need to get 0-10v from HART level transmitter with remote display 4-20ma option. when measured the ma it found 4-20ma with multimeter. when this connected across 500ohms in series, not able to get 0-10v, getting max 3v only. checked with converter which giving 0-10v when 4-10 ma feeded with loop calibrator, but the same 0-10 V not able to get when connected with the transmitter output.
please suggest where the mistake?
4-20 mA over 500 ohm will give you 2-10V. I assume you are using a converter here which is converting this 2-10V into 0-10V.
It seems to me you are getting only 3V because transmitter is not able to drive max. current through the 500 ohm resistance. If you can give us voltage supply for the loop, transmitter power consumption, cable resistance and length of cable, we can calculate exactly to see where is the problem. But as a general remedy in such a case normally if you can increase the loop voltage, the problem will be resolved. For example instead of 24V loop voltage you may use 28V or 30V loop voltage.
But if the transmitter is a 4-wire instrument then the problem may be different. In such a case different ground voltage at two different location creates the trouble.