Tripod Data Systems: Common Questions About Control Files

Common Questions About Control Files

Using Control Files

Because the TDS-48 Series of Data Collectors does not have fast file transfer capability there are some distinct advantages to incorporating the CONTROL FILE into your surveying.

A CONTROL FILE is nothing more than a separate job file in the Data Collector that can be joined together with another job (the open or working job). This allows you to collect new data into the open job, but access any points out of either job. At the end of the day, you only need to download the open job, not the control job. The open job can then be deleted, creating room for the next days work.

One limitation to using a CONTROL FILE is that all of the point numbers in the file must be lower than the point numbers in the open job file, i.e. if you have control points of 1 through 100, you must create the open job with a starting point number of at least 101. The TDS-48 will not take up any memory between the CONTROL FILE and the open job file, so the start point can be any number, as long as it is higher than the last control point number.

To use the CONTROL FILE feature, download the control points into the TDS-48. Then create a new job, changing the START PT: number to the number series that will be collected. Then go to the SETUP menu, and select, SELECT CONTROL FILE. The TDS-48 will display the job directory. Select the CONTROL FILE that was downloaded. This job will now be the CONTROL FILE for all open jobs, until it is deselected (also in the setup menu).

By using the CONTROL FILE feature, you can reduce the file transfer time in the office, protect your control points (the TDS-48 will not allow you to over- write CONTROL FILE points), and conserve memory.

The CONTROL FILE does not have to be called "control file" it can have any name you choose, or it can be ANY FILE already in memory. You can create as many jobs as you need--all starting at increasingly higher point numbers and the control file will work for all of them. Simply backup and delete the jobs that are completed. Once the entire job is finished, the coordinates may be merged in the TFR software to create one large file for conversion and transfer or storage.

When using a Control file the point numbers in the Control File cannot be accessed.

This is typically due to the fact that the job file's starting point is not larger than the largest point you wish to access in the control file. The TDS 48GX will only look for control points that are less than the smallest point possible in the main job file. The main job must be created with a starting point that is larger than the largest control point you wish to access. As an example, if your control points were numbered between one and one hundred, then your main job file must be created with a starting point greater than one hundred. This does not mean the largest number you are using, it means that when the job file was created the entry in the Start point field must be larger that the largest control point you will use. Control point numbers may be used in any screen location in which read only point numbers are legal. They can be used as occupied points or backsight points in surveys and they may be used in coordinate geometry calculations. They cannot be used where a point will be created or modified. They cannot be used as a Foresight Point or as the Store pt: in Intersection or Pt-in-Dir.