FIX: Interix processes do not detect a modem's Carrier Detect signal in Windows Services for UNIX 3.5

Hotfix Download Available
View and request hotfix downloads

View products that this article applies to.

SYMPTOMS

Interix processes do not detect a modem's Carrier Detect (CD) signal in Microsoft Windows Services for UNIX 3.5.

Back to the top

The COM port is not released after an Interix process that uses the port exits. This problem prevents other processes from using the COM port. Processes that are prevented from using the port include non-Interix processes.

Back to the top

RESOLUTION

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support (http://support.microsoft.com/contactus/?ws=support)

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Back to the top

Prerequisites

No prerequisites are required.

Back to the top

Restart Requirement

You must restart the computer because the POSIX subsystem is replaced when you install the hotfix.

Back to the top

Hotfix Replacement Information

This hotfix does not replace any other hotfixes.

Back to the top

File Information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

   Date         Time   Version            Size    File name
   --------------------------------------------------------------
   14-Jul-2004  01:59  8.0.1969.12       131,072  Posix.exe        
   14-Jul-2004  01:59  8.0.1969.12       104,448  Psxrun.exe       
   14-Jul-2004  01:59  8.0.1969.12       763,904  Psxss.exe

Back to the top

WORKAROUND

To work around this problem, configure the modem to make sure that the CD signal is always transmitted.

Note This workaround may have unexpected results in some applications because the CD signal is sent before the remote terminal is actually connected.

Back to the top

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section.

Back to the top

MORE INFORMATION

Interix does not start receiving data from a modem until the CD pin is signaled. The CD pin is also known as the Receive Line Signal Detect (RLSD). Generally, modems set this pin after they negotiate a connection with the remote modem. However, direct computer-to-computer connections are ordinarily configured so that the CD is always signaled.

The modem's settings may affect whether this problem occurs. Also, the problem appears to be more likely to occur with some serial drivers. For example, the problem is more likely to occur on Microsoft Windows Server 2003 than on Windows 2000 Server.

This issue does not apply to direct computer-to-computer connections.

For more information about Windows Services for UNIX, visit the following Microsoft Web site:

http://technet.microsoft.com/en-us/interopmigration/bb380242.aspx (http://technet.microsoft.com/en-us/interopmigration/bb380242.aspx)

Back to the top