How to get status on the number of bytes in the output buffer...

I am writing a program to send UART like messages using a 2 port DIGI Edgeport serial converter. I am using JSSC serial API for Java (v2.8) and before using the edgport could use the getoutputbufferbytecount to status the port for how much traffic it has sent and has to send. This was with older PCs that had serial ports built in.

Since going to the edgeport I can no longer get a solid status on the output buffer byte count and only get returned the initial variable.

Can anyone tell me how I might status this variable from the USB-Serial converter?