At present, some of the field calibrator has little incorrectconnection judging function, for the electric energy metering devices running state detection work is far from sufficient.
目前一些现场校验仪具有少量错误接线判断的功能，对于电能计量装置运行状态检测工作来说是远远不够的。
2
The problem in the communication between DSP and PC based on RS-485 is presented, and the solution of common-mode disturbance and EMI which are generated by incorrect ground connection is stated.