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Is there a need of250 Ohm Resistor for Control Valve Calibration using HART Protocol ? If so how & where to connect the250 Ohm Resistor? Thanks beforehand
u use the shunt250 ohm resistor if the cable resistance is lower than that
This video shows how and why a loop resistance is critically important for the proper operation of a HART "smart" transmitter to communicate.http://youtu.be/XJ4A-0kGGkI
U have to conect in the series of power supply there is not compulsory to connect250 ohm this is impedence matching resistance because in field if control valve or some other instrument connected with loop then there is no need to connect resistance and also u have to consider that the resistance of system loop is not just about same250 ohm this could b very with the manufacturer design .however if u want to calibrate control valve with power supply then u have to connect resistance either in series of -ve or in series of +ve u can also used180ohm resistance instead of250 ohm upto180 ohm hart works ,if not trust then u have to do a practical and reply on this site same forum.
hope for good experiment
no in latest type communicator no need to connect250 Ohm resistance. it is fefault with probes connecting point with communicator
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