Core Electronics Forum

Using the RS485-Pi with a GPS Receiver and GPSD

G’day all,
New here so be gentle…
Just wondering if anyone knows if I can read GPS data using gpsd or similar with the RS485-Pi. My GPS Rx is a commericial timing unit which is RS422 standard.

My project is a GPS Rx testing system, it requires me to have a permanently connected GPS module on ttyUSB0, then I need to be able to temporarily attach the RS422 GPS unit under test and confirm its operation.

Ive bought a usb to rs422 converter but so far can’t workout how to get the gps data out of it.

Any help on this would be great, if I can get this to work on a Pi Zero it would be fantastic.


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RS422 only defines the electrical characteristics of communication, it doesn’t say what data rate or format the data is in. Do you know the data rate? and is the data NMEA data? I don’t have a clue what you are trying to do, but it sounds like take it in steps. Wire the USB/RS422 converter in loop back, i.e. transmitter to receiver, connect it to a computer and use a terminal emulator to test it. Characters typed on the keyboard should echo back. If that doesn’t work the converter is a dud or the wiring is wrong. When that works, connect up your GPS unit. If it is standard NMEA data it should dump to the terminal emulator screen. Once that is working you can consider using a specialised GPS program to do something with the data. Does that sound like a way forward?

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Hi Phil,

What model of GPS are you using? We may be able to hunt down some info on what it spits out on our end with that.

keen to see your system up and running!