Basically a TDS analyzer and meter itself is same as a conductivity meter. The Only difference is the unit of measurement. Conductivity is measured in µS/cm or mS/cm and the TDS is measured in ppm or ppb.
Both conductivity and TDS meters require conductivity cell to measure the conductivity of a liquid. Depending upon the range, conductivity cells with different cell constant (defined as K) are available.
WAVETEK offer both online and laboratory type TDS analyzers. Refer the above section of conductivity analyzers for details with technical specifications of the available models. The same conductivity instruments can be calibrated to measure TDS in ppm or ppb.