Test Serial Ports and Hardware Events

A 'Test Serial Ports and Hardware Events' (previously Test RS232 Signals) utility is supplied with ComCap, which may be useful for simple communications port testing.  It allows any installed windows serial communications port to be open, shows the status of the five RS232 signal lines and whether any data is being received, and allows the DTR and RTS control lines to be raised or lowered.

If a modem is connected to the serial port and it has front panel indicators, toggling DTR will cause TR to flash, confirming that the modem is cabled correctly to the PC.  If a null modem cable is used to connect two PCs each running the utility, the opposing DSR and CTS indicators will appear as DTR and RTS are toggled on each PC.

Some virtual ports may have strange names like CNCA2, but these will work identically to those starting with COM.

This utility does not show or send any data, it’s just designed to ease resolving cabling problems, or even identifying which PC back panel connector is which communications port.

Note this utility only shows serial ports that are exist and enabled, while the ComCap Serial Ports grid in Common Settings shows all ports installed on the PC including those currently removed and unusable, which are typically USB serial ports that are unplugged.