When the system runs with incorrect and unstable measurement data, distinguish whether the problem comes from the instrument or the conductivity cell.

Measurement status of resistivity: Remove the white wire from the wiring terminal of the conductivity cell of the instrument and check if the resistivity displayed on the instrument is 18.23M Ω• cm at full capacity. If it shows 18.23M Ω• cm, it indicates that the instrument is normal and the problem is preliminarily determined to be caused by the installation of the conductivity cell;

Conductivity measurement status: Remove the white wire from the conductivity cell terminal of the instrument, check if the conductivity display of the instrument is zero. If it is zero and stable, it proves that the instrument is normal. It is preliminarily judged that the problem comes from the installation of the conductivity cell;

Short circuit the white and green wiring terminals on the instrument, check if the resistivity display of the instrument is 0.0M Ω• cm. If it shows 0.0M Ω• cm, it proves that the instrument is normal, and it is preliminarily determined that the problem comes from the installation of the conductivity cell;

Distinguish whether (4~20) mA belongs to instrument mode or transmission mode.