arduino has a mysterious port jam

Development Boards Arduino
1

i have 2 unos

my troublesome uno has the On and L leds on all the time ,no blinking .

when i load a sketch to my good uno all goes well via port 5 .

no probs. win7 port5 is fine ,thats where the driver was setup .

but when i try to load a sketch onto the troublesome uno ,it cant find the port 5 and insists i use port 6 .ok i

go ahead and then i get the dreaded cant load avr bla bla bla message .

and when i look in device manager it has changed the port setting to port 6 !!

go back to loading on the good uno and sketches load fine and all is well ,and when i check in the device manager it has been set back to port 5 !!

the bad uno sets my port to the wrong port somehow !!

2

Every Arduino board will have different port numbers. Even if you 5 identical UNO’s, they will have 5 different ports, one for each. The computer OS can see that the device signature has changed.

About your upload problem, you need to give the exact error message and the code you’re loading.

3

it can be any sketch that cause a malfunction and a generic cant load message .

i have swapped out the 328 chip for a known good chip with BL and its still the same .

wont load a sketch and 2 leds always on

4

While connected, the Arduino will not change ports. It is more likely YOU (the human) is getting confused about what ports the boards are being assigned.

Being unable to program the board is most likely unrelated to what com port is assigned.

Since English isn’t your first language, maybe you are having trouble describing your problem. Maybe try in a “1. Plug in Arduino. 2. Look at Device Manager” format instead of a paragraph format. Then we can help understand what the problem is and how to fix it.