What it does

TestRs232 is a Windows tool for testing serial (COM) ports. You write strings that can contain control characters, keep them in a list with a comment for each one, and send them out a COM port. You can send once with a button or repeatedly on a timer. Everything that comes back on the port is shown byte by byte in a hex viewer.

Testing without serial hardware

Install com0com, a free virtual null-modem driver. It creates a linked pair of virtual COM ports. TestRs232 can then send strings on one port to another program you are developing on the other port, even if your PC has no real serial port.