Serial communication mac to Digispark ATtiny85 I want to use the Arduino IDE serial monitor with my Digispark ATtiny85 over USB.

I can without problems upload this code(Digispark CDC example):

#include &lt;DigiCDC.h&gt;
void setup() {                
  SerialUSB.begin(); 
}
void loop() {  
  SerialUSB.println(F("TEST!"));
 //SerialUSB.delay(10);
}


In a terminal, I can confirm, that it indeed creates a new devise:

ll /dev/*usb*
crw-rw-rw-  1 root  wheel   21,  89 27 Sep 10:36 /dev/cu.usbmodem1411
crw-rw-rw-  1 root  wheel   21,  88 27 Sep 10:36 /dev/tty.usbmodem1411


When trying to start the Arduino serial monitor, I get the error:

 Error opening serial port '/dev/cu.usbmodem1411'. (Port busy)


I have confirmed that there are no open files or processes using the USB port. I have the same problem trying to use cu or screen in the terminal.

I have googled the problem, and found that several people has the same problem on new mac computers, but I have not been able to find a solution. -any ideas?


Digispark Rev3 (Chinese clone - with bootloader firmware 1.6 (1.06))
Arduino IDE 1.8.7
Mac OSX High Sierra 10.13.6
SoftSerial and a real serial port on the mac will work. Or if you are careful use the DigiKeyboard and print the debug to the HID keyboard REMEMBERING to switch to a notepad equivalent window on the mac to receive and display the debugging text and not have it overwriting the arduino sketch by mistake.
DigiCDC is a kludge that does not work properly on modern operating systems sorry!