ndzied1
Lifetime Supporting Member
Does anyone have experience using a TDS (Total Dissolved Sensor) w/ a PLC analog input. I have a customer trying to move from a control box and take the sensor directly into an analog input.
He had given me a table of resistances from the sensor which relate to a TDS reading in parts per million (ppm). I had given him a circuit based on DC current but the output from the sensor varied all the time.
Today I finaly got a chance to visit his facility and look at the control boxes he was using with the sensor previously. They all used some form of AC current with the sensor. One was 30V AC 60Hz and another micro-p board seemed to be based on a 5v 30khz signal.
Has anyone had any success with a TDS sensor and straight DC or if not, how would you convert an AC signal to be used with a DC analog input?
Thanks,
He had given me a table of resistances from the sensor which relate to a TDS reading in parts per million (ppm). I had given him a circuit based on DC current but the output from the sensor varied all the time.
Today I finaly got a chance to visit his facility and look at the control boxes he was using with the sensor previously. They all used some form of AC current with the sensor. One was 30V AC 60Hz and another micro-p board seemed to be based on a 5v 30khz signal.
Has anyone had any success with a TDS sensor and straight DC or if not, how would you convert an AC signal to be used with a DC analog input?
Thanks,