GPS Custom Layer FAQ

• Why I can't see my GPS collector?

  GPSLayer uses standard ArcObjects to manage the GPS feed. If you cannot see the GPS collector in ArcMap using the out-of-the-box GPS toolbar, then you are most likely missing a piece of middleware that should be provided by your unit's manufacturer.

• If I manually set the COM port, the layer works. Why, in that case, does the Detect button not work?

  The detect button does not use ArcObjects. Rather, it scans each available COM port at 4800 8 N 1 for the phrase "GPRMC". Some older GPS units may not be configured to send a GPRMC sentence.

• Why am I not seeing the GPS point if the dialog is displaying data?
  1. In ArcReader, be sure to refresh the display after activating the layer. This is a bug in 9.2 that is fixed in 9.3.

  2. Make sure the data frame coordinate system and units are set when the PMF is published.

  3. Check if the map has a reference scale set that would shrink the symbol to invisibility (see below).

  4. (If the above don't work.) I am not sure why, but in the one case reported so far, it was fixed by downloading and installing the .NET SDK. I'm am still trying to figure out the cause and how to prevent it.

• Why does the GPS point get larger or smaller as I zoom in or out?

  If the map has a reference scale set, that will affect the sizing of the GPS point. To disable this, in ArcMap set the reference scale to "None" before publishing to PMF.

• Can I change the GPS point symbol?

  At this time, the only way to change the symbol is to download the code, make the change, and rebuild the application yourself.