Corrupted data over UART?


I’m having trouble while reading NMEA output over UART, after some tries I’ve made a simple program that collects the raw data from the UART and prints it on screen. The result of running this code it’s something that looks like NMEA messages but also has a lot of garbage (See image below).

I have tested the UART communication and it works just fine.
I’m working with ReachView v2.7.1-r0 and reading the data with a Siemens SIMATIC IOT 2000, I have the emlid reach powered with a power bank and I connected both RX->TX as GND->GND. I’m also using the DF13 cables provided by emlid in the reach package.

If there is some information missing I’ll happily provide it.

Any suggestion would be helpful,

Thanks in advance,

Read this?

Thanks for the response,

I have read that link and tried the solutions proposed. Didn’t work; anyway I think I’ll send the data over TCP in order to avoid this kind of problem.

If there is any other suggestion I would be happy of try it in order to have a solution, even if it is for educational purposes.

Best regards,

Do you the same scramble nmea meassage if open with a different application?
Like bluetooth gps or lefebure ntrip?

Interesting. Sounds like you’ve covered the basics of baud rate and connections. Have you tried changing from NMEA output to LLH or ENU format and seeing if you still have garbage characters?

It might be an esoteric setting like your line ending character or the format of the data your monitor is expecting. If you can alter some settings on your Siemens device, or test with some kind of alternative serial decoder you might find the answer. As TB_RTK says, try bluetooth and use a bluetooth to serial app on your phone?

Check you have a location solution in reach view when testing, I’ve fallen victim to that several times… And double double check your wiring, I’ve wasted days on that point.

Looks like you didn’t connect the GND wire.


I haven’t had time to try this, I will comment the results maybe on monday.

I agree, it looks like a ground problem. The GND wire is connected though, maybe the cable or the GND pin in any of the devices is faulty.
Thanks for the response

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I’ve tried bluetooth GPS and sending data over TCP, both work perfectly, no scramble NMEA messages. This supports the idea of a problem with GND. As I said on a previous comment I will get the NMEA messages over TCP, so we can close the topic, even if it’s not 100% solved.

Best regards,

I finally had time to test the board. The problem was that both 5V and GND pins are 0.3V above the expected (In the SIMATIC2000). As I was feeding the emlid reach with an usb cable and connecting it to the board over DF13. So, it was as expected a GND problem.

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