The basic configuration and communication of a virtual machine hosted by VMware ESX to a serial device is supported by VMware.
Support for the functionality provided by various serial devices that can be attached to such virtual machines is provided directly by the device vendors. VMware assumes that the third party device vendor has done the necessary validation to support this configuration in a production environment. In the event that a problem is found, VMware recommends that you open support requests directly with the third-party vendor's support organization. VMware collaborates with third-party vendors via Technical Support Alliance Network (TSANet) or Cooperative Support Agreement (CSA).