Arduino stops uploading for no reason

I built a Folger Tech Kossel 2020 delta printer and I'm using the Marlin firmware. The folgertech arduino mega clone that came with the kit burned out, so I'm on my second board, still a clone but seemed to work...at first.

I plugged it up and powered it on and uploaded the marlin firmware. Seemed fine. Then I plugged all the components into the ramps board. Wouldn't upload. Unplugged everything. Plugged them in one at a time. Started working again and would upload fine. Then I began configuring it and changing numbers. Saved it to where I had downloaded it to my mac. Got an error saying there was a problem uploading. Redownloaded the software and uploaded it everything seemed fine. Changed two configuration numbers and DID NOT save. Everything was fine. Changed another number. DID NOT save. Got the same error.

Sketch uses 101,174 bytes (39%) of program storage space. Maximum is 253,952 bytes.
Global variables use 4,531 bytes (55%) of dynamic memory, leaving 3,661 bytes for local variables. Maximum is 8,192 bytes.
avrdude: ser_open(): can't open device "/dev/cu.usbmodem1411": Resource busy
ioctl("TIOCMGET"): Inappropriate ioctl for device
ioctl("TIOCMGET"): Inappropriate ioctl for device
avrdude: ser_send(): write error: Bad file descriptor
Problem uploading to board. See [www.arduino.cc] for suggestions

I've been trying to get this working for months and it just seems to arbitrarily stop.

Please help if anyone else is having issues with this.

Edited 1 time(s). Last edit at 12/01/2015 03:48PM by amandarh92.

Last time i had something like that it was on my laptop and i thought the board was messed up. I reboot the pc and same problem.
I ended up uninstalling the drivers , reboot and reinstalled and all had been find since.

You can't have pronterface and arduino talking to the board at the same time. Disconnect pronterface before uploading.

Is your Powersupply of the printer plugged in when having this problem?

If not - I had the same issue with an cheap, long USB-cable (AWG26 wires) - simply not getting enough power over this cable... replaced cable by a shorter, better one (AWG22 wires) and everything works fine.

I did have the problem with it not being connected to the powersupply with the first one but this time the power supply was plugged in. I am working on a mac so there might be a problem there. I'll try shutting down pronterface and see what happens. I downloaded the newest version of arduino as well so I'll see if that fixes it.

I get checksum errors uploading to either of my mega boards if I use the USB mouse whilst the upload is in progress. Leave the mouse alone and it uploads fine.