SGM is a plugin component that allows an AP developer to provide his/her application software with the capability of reading information from a GPS receiver that delivers a NMEA 2.0 and above compliant sentence. Technically, it is a component of Spatial Information COMponents (SICOM). Upon startup, the GPSreader attempts to connect itself to the comm port given by the environment variable GPS_PORT, and then presents its GUI. If connection to the given port is successful, the GUI's "Port Status" field displays the message "Connected to port xxxx", where xxxx is the name of the port, e.g. COM1, as given by the environment variable. If connection is not successful, the "Port Status" is "Disconnected" and the "Error msg" field displays one of the following messages: 1) "Unable to open port xxxx"; 2) "Could not find environment variable GPS_PORT". Message #2 is self-explanatory. There are two possible causes for message #1: 1) the specified port does not exist; 2) the specified port is already in use by another process. Under any of these circumstances, it is necessary to terminate GPSreader, correct the problem, and restart GPSreader.
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