RM Frobisher – SD Cards

SD Cards, Files and File System

This Application Note is written to accompany RM Frobisher (1986) Ltd's TAR-3 Resistance Meter Operator's Manual. It contains details of the SD Card and the files stored on the SD card used in the TAR-3 Resistance Meter.
The TAR-3 Meter uses "micro" Secure Digital Cards (SD Cards) which can easily be misplaced or lost (left in other equipment). It is good practice to always carry a spare FAT32 formated SD Card

The TAR-3 Resistance Meter must have a FAT32 formated SD Card fitted to function.
If a SD Card is not fitted the TAR-3 unit will not work!

SD Card

The SD Cards supplied with the TAR-3 Meter are standard 8MB cards formatted with a FAT32 file system which is standard (in 2015). New high capacity cards may have a different format. Check the format of any replacement cards before using a new one!

Checking a SD Card's format

The TAR-3 Resistance Meter uses standard SD Cards available from any supplier. The cards do not have to be high speed or high capacity.
Using a PC or laptop running a MicroSoft® Operating System (Windows 7, 8 or 10):

  • Insert the micro SD Card into the adaptor or holder,
  • Navigate to the “My Computer” or “Computer”,
  • Right click on the SD Card’s icon and select “properties”,
  • The File system must be FAT32.
  • If the SD Card’s File system is not FAT32 the SD Card must be formatted with FAT32.

    Formatting the SD Card is will delete all of the data on the Card! Do not format the wrong disk or card!
  • Right click on the SD Card’s icon and select Format... (make sure it is the correct disk – check the disk size is 8MB, or the size you are using!)
  • Select FAT32 and format the removable 8MB disk
  • The SD Card is now ready for use in the TAR-3 Resistance Meter.

Insert the SD Card into the TAR-3 Meter and switch it on. The TAR-3 unit checks the card for errors and free space during power up. (This can take several minutes the first time a new card is used).

Files and Data on the SD Card

TAR3DATA.TXT
A plain text file containing your results. This file can be opened and edited with "notepad.exe"®. You can use any Text editor. Do not use MicroSoft Word or word processing software to edit this file. This file is imported into "snuffler"© software.
Other "system" files are:
TAR3_N000.SET
This file contains the default settings or the last settings used. It is a "binary system" file and cannot be opened or read by the user.
SWAP_N000.SWAP
This is a "binary system" file and contains the results of the last grid. It is "Back up" file. It stores the data in a compact binary format and it can be used to recover the results from the last grid.
When starting a new grid the above files are renamed TAR3_N1.SET and GRID_N1.DAT up to TAR3_N99.SET and GRID_N99.DAT
GRID_N1.SET
A "binary system" file. It cannot be opened or read by the user. It contains the settings used for grid number one.
GRID_N1.DAT
A "binary system" file. It cannot be opened or read by the user. It contains the readings recorded for grid number one.

The TAR3DATA.TXT file is the main file it contains your results. If this file is deleted it is recreated and the results added to it. The SET, SWAP, and DAT are system files and cannot be read. The DAT and SET files are compressed backup files and are there to provide data security.

Retreving Your Results

To transfer your results to a computer:

  • Open the hatch on the back of the TAR-3 Unit.
  • If the unit is powered on – press the 'Off' button.
  • 'Push' the SD Card into the socket and allow it 'spring' out.
  • Now ease the card out of the socket.
  • Insert the Micro SD Card into the USB micro SD Card reader (or into the micro SD Card to standard size SD Card adaptor).
  • Insert the adaptor, or reader, in to your PC.
  • Copy the TAR3DATA.TXT file from the SD Card to your PC.

The TAR-3 Meter can store up to 99 grids on the SD Card. If you delete the TAR3DATA.TXT file from the SD Card a new file is created by the TAR-3 unit when the next grid is started. The Grids in the file will be sequentially numbered following on from the last grid number. To restart the grid numbering from one, all of the files on the SD Card must be deleted (or the card formated).

Deleting all of the files removes all of the backups! Make sure you have a copy of the data you need before deleting the files.