The system and manner null for the safe detect automatically of the field device which is communicated with the electric current modulating signal

摘要

The electric current generator which offers the 1st electric current level in order to grasp the constitution parameter of the field device. In addition as for the electric current generator, it offers also 2nd electric current level. 1st as for electric current level, 2nd amperage is smaller than electric current level. 1st electric current level does not operate the field device. 2nd electric current level operates the field device. The electric current sensor the field device is connected with the circuit. The electric current sensor grasps the constitution parameter which it is related with 1st electric current level. The method of forming the electric current which grasps constitution parameter is offered. Amplitude of the electric current, although the field device is operated, necessity, is smaller than the smallest amplitude for operation. Using the electric current, constitution parameter is grasped from the field device. The field device is formed, using the constitution parameter.