What is "open of \\.\COM## failed with 5 [Access is denied.]" error in Predator DNC?

What is "open of \\.\COM## failed with 5 [Access is denied.]" error in Predator DNC?

Problem

The logs in Predator DNC show a failed with 5 error.

Reason

Indicates the COM port is in use and unable to be opened by Predator DNC. 

Solutions

  1. Occasionally some network-based devices do not release the port fast enough causing a false error; simply restarting DNC might do the trick
  2. Close any additional PXPs that may be open (Close Additional PXP Configuration File)
  3. Check if another machine in Predator DNC is using the same COM port
    1. Stop all machines, then start only the problem machine.
    2. Wait one minute and see if it has the "Access is denied" error. If not, start the remaining machine and see what other machine now has an "Access is denied" error. This is likely the conflicting COM port. 
  4. Check if another DNC application is using the COM port
  5. If using network-based hardware such as a Moxa, confirm no other application is connecting to it