The Driver use COM port of the computer as parallel!
You have 2 lines on the write and you have 4 lines on the read.

You can use the TxD line for data transmitt! The driver is the ActiveX. You can use its in some Programming language. (ActiveX™ is registered trademarks of Microsoft Corporation). Your device must be the V.24 compatible (CCITT standard for definition of circuits between a DTE and DCE)