OPenCPN does no longer receive UDP-messages from ESP8266

[StefanL38]

Hi everybody,


I'm supporting two people with a sensor how much fuel is still in the tank.
This is done with a microcontroller ESP8266. This microcontroller connects to the boats Wifi and then sends NMEA-Data over WiFi-UDP to a laptop running OpenCPN.


The receiving of the data was working. Now after some minot changes but no changes to how the WiFi-connection works OpenCPN does no longer receive the UDP-messages. Port is correct.


If I connect the ESP8266 microcontroller with USB-cable openCPN is able to receive the NMEA-data.


I have some questions in the Options window the IP-adress is 0.0.0.0
The ipV4-IP-Adress of the laptop is 192.168.1.225


If I look up the Arduino-IDE serial monitor I can see UDP sended to 192.168.1.125. Difference .225 to .125



Doe this mean the ESP8266 is just sending to the wrong IPadress?
Does UDP need a receiver-IP-adress?


Is there a broadcasting IP-adress that could be used so all devices in the same network can receive the UDP-messages?


What can I do to narrow down the problem?
Can you recommend an android-App that can send pre-configured UDP-messages. For testing the receiving?


Where can I read in the manual about what UDP-setting does what in the OpenCPN-options Window?


best regards Stefan

[PippaB]

Yes, UDP needs a destination, so it looks like you are sending to the wrong IP. If supported by both sender and receiver you can use a broadcast address. The broadcast address is the highest address in the subnet, likely 192.168.1.255 in your example (that assumes a netmask of 255.255.255.0 or /24). Many UDP senders will accept 255.255.255.255 as a generic broadcast address so you don’t need to know or program network particulars, I don’t know the particulars of the ESP8266 capabilities.

[merrimac]

Note that if you send (any) data to a broadcast address over WiFi, these packets will consume an extraordinary amount of bandwidth as they are generally sent on the lowest common data rate.