DJJ adder is one unit of DDZ-Ⅱseries of instruments .It can do addition operation with the output signal of transmitter or regulator, then sent the signal 0～10mA to the next checking instrument. It has four input channels. two types : DJJ-04 adder ,can do calculation with foreign signal(transmitter or regulator ),then sent the unified signal 0～10mA to the next checking unit.

DJJ-21 adder can do calculation with  positive and negative signal of regulation system..