9.432 NMEA-GPS-Receiver

This page describes the device driver and the device window for GPS receivers offering the NMEA 0183 protocol through a serial interface.

The sat-nms device driver for this device family passively reads the data stream output by the GPS receiver. From the received data the driver extracts the GGA (Global Positioning System Fix Data) sentence and parses it.

Important Notice

Due to the fact that the GPS receiver perpetually sends it's data to the VLC, it is essential that the idle time of the device thread / interface serving the GPS receiver is set to 10 msecs. The default value of this parameter is 1000 msecs which leads to frequent read timeouts / misinterpretations due to overruns of the VLC serial interface input buffer. The idle time parameter may be changed with the interface properties at the device setup editor.

Device window pages

The following table shows which device window pages are available with this individual device type. Tool-bar functions not mentioned here are described at the general description of device windows .

• --- The main parameter page shows the GPS parameters read from the device.
• --- The faults page.
• --- The device info page.
• --- The maintenance page. The configuration parameters described below are set at this page.

Configuration parameters

The only configuration parameter which must be set is the line speed of the serial interface. GPS receivers usually work at 4800,N,8,1 .

Variables defined by this device driver