COM Port Settings in Control Panel vs. Command Prompt

ID: Q112841

The information in this article applies to:

Microsoft Windows NT operating system version 3.1
Microsoft Windows NT Advanced Server version 3.1
Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0
Microsoft Windows NT Server versions 3.5, 3.51, 4.0

SUMMARY

The COM port settings in the Ports option of Control Panel have no effect on COM port settings used in a command prompt window.

MORE INFORMATION

MODE.COM queries the port directly. Default settings are the following:


   Status for Device COM1:
   -----------------------
    Baud:            1200
    Parity:          Even
    Data Bits:       7
    Stop Bits:       1
    Timeout:         OFF
    XON/XOFF:        OFF
    CTS handshaking: OFF
    DSR handshaking: OFF
    DSR sensitivity: OFF
    DTR circuit:     ON
    RTS circuit:     ON

Applications reset the mode of the COM port(s). If, for example, you start Terminal and reset COM1 to 14400 baud, 7 data bits, odd parity, then exit Terminal, the new settings remain in effect until the computer is shut down. Upon rebooting, the default settings are once again in effect. The Control Panel settings, on the other hand, affect the registry. An application that is appropriately written can query the registry for these values and use the Control Panel settings. The default settings in the Ports option of Control Panel are:


   Settings for COM1:
   -------------------
   Baud Rate:     9600
   Data Bits:     8
   Parity:        None
   Stop Bits:     1
   Flow Control:  None

Additional query words: prodnt 3.1 3.5 4.0


Keywords          : kbhw nthw 
Version           : 3.1 3.5 3.51 4.0
Platform          : winnt 
Issue type        :

Last Reviewed: February 2, 1999