DP4-R high- impedance ohmmeter adopts high- precision IC chip design with high stability and strong anti-jamming. The ammeter adopts modular structure output function such as high or low limit alarm, current transmission:4-20mA and 0-10mA output and RS485/RS232 communication etc. The value of high or low limit alarm, corresponding measured value and transmission output value can be set optionally. The modern advance MODBUS communication protocol is available, with maximum bound rate 19200 bit/s. The input port of ohmmeter I 5VDC small voltage, without damage to the measured object. The biggest impedance of the meter is 200MΩ. The DP4-R ohmmeter is designed as measured meter for internal resistance of the battery product.