When using UDP, is it realistic to send a message and expect it to be received?
Or is it more likely that multiple copies must be sent? Thus, requiring an acknowledge in the code?
In a local area network, it probably will be received with no issue. On a wide area network (like the Internet), there is no guaranty.
If you require an acknowledgement, why not use TCP to begin with?
I ran simple test code over my local WiFi network, can't remember exactly but maybe 0.1% failure rate, by which I mean lost, duplicated or errorred packets.
That’s what I thought. However, someone else stated that my code was wrong because it only sent a message once.
I have 6-10 devices and any one must be able to talk to any other. The message is 1 to 3 characters. UDP seemed to be the best choice.
The code runs on a MEGA2560 with an Arduino Ethernet Shield, hardwired together with a crossover cable, but will run through a switch.
However, someone else stated that my code was wrong because it only sent a message once
You have to decide if errors or lost packets are acceptable and write code accordingly. Sometimes I make it so the same data has to be received twice or 3 times before it's accepted as valid.
UDP is dead simple to use, but you pay for that simplicity with errors.
Dead simple... but I can’t get two characters from one machine to the next.
I expect that the problem lay not with UDP, but the Arduino Ethernet libraries and how I’m using them.
There is a lot more information in this post!
https://forum.arduino.cc/index.php?topic=681940.msg4587512#msg4587512