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CN0359 voltage build up, leading to error?

Question asked by Ben.VDK on May 30, 2016
Latest reply on May 30, 2016 by R.L

Hello all,


I have a 4 pole conductivity probe with 4 wires and a shield, also a 3 wire pt 100 temperature sensor. When connected to the CN0359 they both work.


The probe, for a test, is placed in a NaCl 0.9% solution, there are no changes in the fluid. After a short time the value from the conductivity probe goes up rapidly and than the CN0359 gives the "Sensor Incorrect!" error. When I reset the CN0359 (power off and on again) the value resets and again after a short time the value rises, with the error as a result.


It looks like somewhere there is a voltage build up which causes the given conductivity to go up. I am not certain whether the probe or the CN0359 eval board is the cause of the problem. So my question to all the readers is: Has anyone else experienced this or has anyone have an idea what causes this?


Additional information:

Excitation Voltage is set to 200 mV

Excitation Frequency is set to 1.0 kHz

Temperature Coefficient is set to +1.00% per deg. C

Cell Constant is set to 1.00/cm (this value might not match the probe, but other settings have the same result)


Kind regards,