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)

• Simple RS 232 monitor 1.1.0.446
  Simple RS 232 monitor is a small diagnostic program used to monitor RS 232 communications between devices. Usually, one device is a computer. The software supports baud rates from...