Delta-T Profile Probe and HH2 reader

M-Log can graph data from the HH2 hand-held portable data recorder, manufactured by Delta-T Devices.

The HH2 can read and record data from the Profile Probe (PR1), ThetaProbe (ML1 & ML2), and Equitensiometer (EQ1 & EQ2).

The PR1 has 4 (or 6) capacitance soil moisture sensors on a rod which can either be taken from site-to-site to record readings, or it can be left at a single site with a logger. The HH2 is only used if the PR1 is used in portable mode - if the PR1 is left at a site with data recorded by a fixed logger M-Log needs to be configured for that logger.

Data is downloaded from the HH2 and then processed to distribute it to a separate data file for each site.

Use LoggerMenu/Upload/DeltaT-HH2...

HH2 Upload Process Screen (11552 bytes)

  1. Click Upload
  2. Click Process

You will now be able to graph the data by clicking on each sensor.

Installation and configuration is described below - for further details see the M-Log manual.

Installing M-Log

Install M-Log from CD (D:\MLOG\SETUP.EXE) with...

  1. Click on Start
  2. Choose Run
  3. Enter D:\MLOG\SETUP.EXE (or use Browse)
  4. Follow the setup wizard with Next, Next
  5. If supplied, install M-Log upgrade from disk (A:\UPGRADE.EXE)
  6. Run M-Log from Start/Menu or icon.

The sample database of loggers and sensors will be listed - click on a sensor to plot the sample data.

Installing Licence

M-Log needs to be licenced to allow changes you make to be saved (It will, in practice, run for 30 days before a licence is essential).

  1. Use FileMenu/Licence
  2. Click Install
  3. Email or fax the PC Serial number and you will be sent a password.
  4. Enter the password.
  5. Click Activate

Create a new database for your loggers

You can create a new database for the PR1 data...

Use FileMenu/New/Database, and choose C:\MLOG\MLOG1.MDB.

Alternatively you can add new loggers to an existing M-Log database.

New loggers and sensors will be created after readings are uploaded and processed.

Taking readings with the PR1 and HH2

  1. Connect the PR1 to the HH2.
  2. Enter the site number as DeviceID (1-255) with...
    Set Data Set Up 502 Set
  3. Record the data with...
    Read Save data ? Set


  1. Connect the HH2 to the PC with the RS232 cable.
  2. Run M-Log, and use LoggerMenu/Upload/DeltaT-HH2.
  3. On the Upload tab choose the correct port (default = Port 1)
  4. Click Upload

The data should now be in a file called: ddMMyy.UPL - it can be checked using edit.


  1. On the Lookup tab choose the method of identifying each site.

    Choose Plot/Device/Sample (11552 bytes)

    If you use DeviceID new loggers and sensors will be automatically created, with the new logger number the same as the DeviceID entered into the HH2 at each site. The lookup file will not be used.

  2. Click Process to distribute the uploaded data to a separate file for each site - it can be checked using Edit on the Process tab.

If a logger does not exist with the same number as the DeviceID number, you will be prompted to create a new logger (site).

A new logger (or site) can be created by copying either...

  1. One of your own existing loggers that has already been customised.
  2. A template logger

If more than one tube is installed at a site, and each tube is given the same site identifier, the data can be averaged.


Averaging several tubes at the same site - if you are taking continous readings at a single site each set of readings must be more than 'minimum time between scans' apart, otherwise all the readings will be averaged.

If multiple theta probes are being used at each site the HH2 is connected to each sensor in turn, and a separate DeviceID number entered. A lookup file must be used, with the column (or depth number) of each sensor entered in the lookup file. If continuous readings are being taken at the same site each set of readinmgs must be more than 'minimum time between scans' apart.

HH2 Commands

After uploading and processing the HH2 memory is cleared with...

  <Set> Data <Set><Up> Erase <Set> Erase ? <Set>

The HH2 is configured for use with a PR1 (access tube) with...

  <Set><Dn> Device<Set><Up><Up> PR1 <Set>

The HH2 is prepared for uploading with...


Use LoggerMenu/Upload/Delta-T HH2 GetStatus to show the current battery and memory status of the HH2.


The HH2 converts the output of the profile probe from volts to soil moisture. The Delta-T Profile Probe manual provides a polynomial and a linear equation, for both organic and mineral soils.

The HH2 appears to default to the polynomial equation. However a trial in Australia showed that the linear equation gave better agreement with measured applied water at high moisture contents.

Both M-Log and Probe for Windows can have calibration equations entered, allowing the use of the linear equations and to change the equations at any time in the future. If you are going to use this feature the HH2 should be set to ouput in mV.

Profile Probe User Manual, page 18

Equations to be entered into M-Log and Probe for Windows to convert from mV -> % (0-100)

Organic: Slope = 0.129 Intercept = -0.11

Mineral: Slope = 0.140 Intercept = -0.08

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