HF Scientific MicroTOL Turbidimeter

Importance of Getting the Detailed Data

The MicroTOL Turbidimeter manufactured by HF Scientific is used to monitor the influent and effluent turbidities of the laboratory flocculator setup. In the current experimental setup, we are obtaining data from each turbidimeter in increments of 1 second using Process Controller.

The MicroTOL Turbidimeter is outputing a light sensor, that is then translated into an electrical analog data set that can be read by the computer to output a NTU reading. The frequency of the analog data is a lot faster than 1s, and is averaging the data to give the user a reading every second.

For our experiment, we are trying to find the smallest changes in turbidity over the smallest amount of time. By looking at this "raw" analog data, we might be able to draw better conclusions about particle size and sedimentation than the analyses with the averaged data. We are currently in contact with HF Scientific to determine how to obtain this analog data.

Contact Log with HF Scientific, Inc. Technical Support

Friday, February 15th

Gemma talked with Phil in technical support. It is possible to get the "Raw Data" and we can do this by incorporating MODBUS communication programs. Phil does not know the exact timing of the analog signal, but he believes that is as low as 250 milliseconds (maybe even lower), however, he also said that we might not be able to get a clear enough (readable) signal until we reach 750 milliseconds. He will figure out the exact number and respond next week.

To read the raw data, we need to user Hyper Terminal, a Windows program that can bee accessed under Windows>Accessories>Communication. The HyperTerminal manual should be read to figure out exact settings/configurations to read from Modbus. Next, we have to buy the Modbus program package (or this might come free with HF Scientific software).

Monroe's comments: We are already using the modbus (not sure on this terminology, but we are definitely using RS485 communication protocol) to get the data from the instrument. And I think we are already getting a data point every second. The process controller software uses serial communication (in a more sophisticated way than the hyperterminal approach) to get data from the turbidimeter. If we can get an analog signal then the meaningful data rate will only be limited by the detector (sensor) response characteristics. Check out: Floc Strength Measurement