Horiba Waterproof pH, Temperature, and Conductivity Meter, Model D-54 Report by YiSeul Park; Spring 2006

There are number of important elements we consider when we check our health conditions. Among those elements, the pH and the conductivity of the urine have the strong point of possibility of getting the measurement result right away. The pH of the urine shows whether the body absorbs the essential minerals well and the conductivity of the urine shows how much water the body needs to drink. A healthy individual has the pH of slightly acidic. Strong acidic urine shows the evidence the person eats too much meat or greasy junk food. This case, he/she might want to see the advertisement of an organic vegetable shop. If the urine conductivity is higher than normal, this suggests he/she needs to drink more water. In this case, he/she will see the advertisement of the mineral water. I built the smart toilet system that measures and analyzes the pH and the conductivity of the urine real time. With the urine condition, the system shows the customized advertisement. The toilet I used is not a special kind but an ordinary one with the modified specification. The screen for the advertisement is placed on the door inside the cubical (the wall you face when you sit on the toilet) ....read more

Facts on pH and Conductivity

     - Acid Alkaline Imbalance
     - The Importance of Your Body pH Balance
     - Too conductive means you are taking too little water.


This pH/conductivity meter contains two input channels which measure pH and conductivity of the liquid. Each input channel has an electrode connector that connects the sensor and the meter. The meter doesn't necessarily have to measure pH and conductivity at the same time. If only one is measured, unused electrode can be covered with a cap to prevent getting wet from water. The power is supplied with 2 AA size batteries which last for 100 hours. Instead of using batteries, 100-220V AC adapter can be used as well; however, it needs extra care. When the AC adapter is connected, the meter is no longer waterproof.


You need to buy electrode sensors (pH or conductivity)seperately from Cole-Parmer

Taking Measurements

    1. Turning the meter ON/OFF: Press the ON/OFF key for the power on/off 
    2. Setting required before measurement:
        1) Setting the clock: The built-in clock allows you to record the date of calibration and data memory storage.
        2) Setting the measurement mode: There are two types of measurement modes: Instantaneous value measurement mode and Auto hold measurement mode.
                (1) Instantaneous Value Measurement mode: This meter performs instantaneous value measurement as the default measurement mode when the power is first turned ON and when the auto hold measurement is cancelled or cleared.
                (2) Auto Hold Measurement mode: Auto Hold Measurement mode maintains the display of the value measured when the meter automatically judges that the measured value has stabilized.
                Press the MEAS key with the Instantaneous Value Measurement mode to make "HOLD" blink on the display.
                When the measured value becomes stable, "HOLD" will stop blinking and remain displayed, and the measured value will remain displayed. To clear the hold status or "stabilized" value, press the MEAS key.

pH measurement

    1. pH Electrode preparation: place pH electrode into input channel 1
    2. Standard solution calibration: In order to measure it accurately, it is important to caliber before the measurement. The correct method is to dip the electrode into the standard solution before the first measurement, which enable the meter to measure the correct pH. The standard solution consists of different pH solutions, normally pH4 and pH7, but to be more accurate, 3 solutions can be also used.
        The electrode needs to be placed at least 3 cm in the standard solution.
        Then, press CAL key to start calibration. Calibrate it per each solution, and wash it with water in between the calibrations.
    3. Measuring pH:
        1) Wash the tip of electrode well with pure water, and then wipe with tissue paper.
        2) Open the internal solution filler port. Leave the port open while measurement is taking place.
        3) Immerse the electrode all the way in the sample. Immerse the pH electrode in the sample at least 3 centimeters.
        4) Press the MEAS key.

Conductivity measurement

    1. Conductivity Electrode preparation: place conductivity electrode to input channel 2
    2. Select the Conductivity Measurement mode when the pH measurement mode is displayed by pressing the MODE key.
    3. Standard solution calibration: The same method applies to conductivity calibration, but potassium chloride is used as the standard solution.
    4. Measuring conductivity: Same as pH measurement.

RS-232C Communication

The following data transfer format is used by the meter.

    - Baud rate: 2400 bps (Data processing speed is slower than common 9600 bps.)
    - Character length: 8 bits
    - Parity: None Stop
    - Bits: 1

When creating a program for RS-232C, put the meter in the ON-LINE mode(RS-232C Serial Communication is ON) by entering an on-line command at the beginning of the program. The control switches become invalid when the meter is in the ON-LINE mode, and the RS-232C Communications mode is enabled. The ON-LINE mode is cleared when the power is turned OFF. Use as the terminator for serial communication commands. All the commands are valid only in the ON-LINE mode. The meter turns a response to any operation made in the following format: OK If the meter does not accept the operation, it returns an error message in the following format: ER,n (It shows a specific error number n, and you can find the solution from the manual book.)

Command consists of Header and Command code. (Header, Command, [CR] [LF])

You need to translate the command to ASCII numbers if you are working with Jitter.see ASCII table

        - Switching between ON-LINE and OFF-LINE
        C, OL, x [CR][LF]
        (In Jitter you need to write this command in a way of 67 44 79 76 44 49 13 10 rather than C, OL, x [CR][LF])

        - pH measurement mode designation
        C, PH, x [CR][LF]

        - Conductivity measurement mode designation
        C, CO [CR][LF]

        - Measurement request
        R, MD [CR][LF]

Code Samples

     1.  Processing Code

import processing.serial.*;

Serial myPort;

void setup() {

  myPort = new Serial(this, Serial.list()[2], 2400);


void draw() {

  if (myPort.available() > 0) {


void keyReleased() {

  if (key =='f') {
    myPort.write("C,OL,1\r\n");  //ON-LINE

    if (key =='g') {
    myPort.write("C,OL,0\r\n");  //OFF-LINE


     2.  Jitter Code