This error is caused when the milling PC loses connection with the milling machine.

Here are some common solutions to solving Runtime Error 8018:

1.  Disconnect and reconnect USB cable from PC and the milling machine

2.  Ensure you have a direct connection from the PC to the milling machine (USB hub not recommended)

3.  Restart PC and milling machine

4.  Ensure your USB cable is less than 3 meters

5.  Ensure the power cable and USB cables are not tangled / twisted together

6.  Ensure your PC does not go into Sleep or Hibernate mode during milling.

Related Article:  Disable USB Selective Suspend Setting