Getting all the different sources of NMEA
183 information and using devices together is the job of the multiplexers as mentioned above. Since NMEA
183 is a sequential type data stream, each piece of electronics
outputting NMEA sentences needs to have its data placed in a sequential stream (one message after the previous message like ducks in a row). Otherwise each device would be "speaking" at the same time and conflicting with each other.
- - But the other important aspect of devices that send and receive/display NMEA sentences is that there are hundreds of different sentences that are used to transfer data from one device to another - and - not all devices can use or read all of the various sentences. So some devices may not be able to display a particular piece of information it receives. The software
engineers for the display device only enable their device to display a limited variety/amount of hundreds of NMEA data sentences.
- - So just because your "outputting" device is sending the information does not mean that the your display device will be able to display it. You need to consult the operating manual for each device to find the ones that will talk to each other and display the information you want.
- - Here is a link to a discussion of the various NMEA sentences and all the various "propriety" versions individual manufacturers have added to the basic list of sentences. As you just scroll down you will see how many different versions there are as each manufacturer wants to add new ones.