# Pronterface won't connect to my Anycubic Kossel Linear Plus

For the Anycubic Kossel Linear Plus I have to upload data to the 3D printer from a software called Arduino and then close it. Then I open Pronterface and put in the right port and baud rate that is in the Arduino files and then click "connect". Afterwards it says

connecting...


and that is all it does and doesn't fully connect to the printer. I've tried changing the baud rate and port in Pronterface, Arduino and the bit rate in the Device Manager but nothing works.

Any suggestions on how to fix this?

• What happens if you disconnect and then reconnect the USB cable? Does Pronterface connect then? Has it ever worked? May 9 '17 at 3:25

I know this is coming very late, but I'll post anyway in hopes that it may help somebody else experiencing the same frustration.

I received all of the same suggestions again and again on the forums -- about baud rate, COM ports, and a lot else which failed to get Pronterface to connect.

At last I posted to the Anycubic User Group on FB, and quickly received what was in my case the solution -- and so ridiculously simple.

I was told to hit RESET two or three times on Pronterface after hitting CONNECT. Yup, that did it!

Good luck!! :D

I know this may be a little late, but I bought the same printer and found that I had problems also. To fix this connection issue I first made sure I had no arduino programs open that were trying the connect to the printer. These would not allow Pronterface to connect to my printer. Then if I still had issues I opened up task manager on my computer just to make sure I had no other programs trying to communicate with the printer. Then if it still can't connect I closed Pronterface and reloaded it a couple of times.

Only one application can access the Arduino Mega board, via the COM port, at a time. Sometimes, the software can get confused, and keep hold of the COM port, although this is unusual.

For example, if you are connected to your board via Pronterface, and without clicking on Pronterface's Disconnect button first, you then try to upload some code to the Arduino via the Arduino IDE, the Arduino IDE will just sit there complaining that it can not connect - usually with an error, or a timeout message, like this:

avrdude: stk500v2_ReceiveMessage(): timeout


See the video tutorial, #18: Calibration, by BuildA3DPrinter. It is a long video, but extremely informative. At 2:20 he has this exact problem. In fact, throughout the video, the instructor constantly reminds the viewer to disconnect from Pronterface before attempting to upload new firmware via the Arduino IDE.

Now, I know that this is the opposite of your issue, as your can not connect using Pronterface, after using the Arduino IDE, as opposed to the other way around, as shown in the video. However, the solution is most probably the same... Momentarily, disconnect the Arduino board from the USB (i.e. unplug the USB cable for a few seconds and then reconnect it). Then, without using the Arduino IDE, now try to connect Pronterface. It should now work - assuming that you have selected the correct COM port, baud rate etc.

I recently purchased and assembled the Anycubic Kossel Delta printer and ran into the same issues.

I found that if I tried to connect with "COM 1" first, it would error out, then when I switched to "COM 4" (the correct port), it connected. Weird, I know, but it works.