Good day,
Let me try to clarify the situation.
RUT850 does not support "GPS coords upload" by a single file.
What RUT850 uses is a proprietary GPS protocol for data transfer, hence it is not a single file, but rather set of rules that is followed in order to send (by the router) and receive (by the server) GNSS and other data.
You can find this protocol described in exact terms here:
https://wiki.teltonika.lt/view/RUT850_GPS_protocols
As well as an example of a packet here:
https://wiki.teltonika.lt/view/RUT850_GPS_protocols#Example
If you find this answer helpful, consider letting me know.
And if you find that you still need clarification or otherwise additional assistance - i shall be glad to assist further.
