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Error trying to use Serial Port connection

I have a serial device that up until today was working fine.
This is a constant feed from a scale to a serial port on the back on the PC.
I am using Windows XP SP3

I can get the feed to work just fine through Terminal Operator, but not in the Application this feeds into.
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The Application it feeds into is a program written in VFP6
The error I am getting is :

Run-time error '8015':
Could not set comm state, there may be one or more invalid communications parameters.
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I have searched online and some people thought it was a Printer Driver issue. I tried uninstalling ever Printer and Printer driver but that did not help.

I also did a full uninstall of the serial Comm Ports and then did a reboot to reinstall them but that did not work as well.

Any ideas what else I can try?
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adam_daunhauer
Asked:
adam_daunhauer
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1 Solution
 
Levi GwynCommented:
COM (serial Ports) are notorious for dying.  The old RS232 standard is not very tolerant of voltage spikes and static.  It may be that the COM port is dead.  If you can dig up an old serial mouse or some other serial device, test the port.  If it fails, you can buy add-on serial cards cheap to replace the port.

This is a total guess but always good to rule out hardware first.
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adam_daunhauerAuthor Commented:
The port is not dead. I can see the scale feed coming through on Hyper Terminal so I know the scale is communicating with the port.
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Levi GwynCommented:
Okay.  Sometimes the addressing of the COM port can get jacked up.  You may have already looked at this but make sure your ports are set to the default values.  The following list is the defaults:

COM1 -  3F8  IRQ4
COM2 -  2F8  IRQ3
COM3 -  3E8  IRQ4
COM4 -  2E8  IRQ3

This article explains how to make those settings changes in XP:

http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/devmgr_changing_port_settings.mspx?mfr=true
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adam_daunhauerAuthor Commented:
Replaced COM port and it is working now. I guess it was a bad COm port. Strange that there was a feed at all.
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Levi GwynCommented:
Glad I could help.  If this is a mission-critical system, you can run shielded cable and ground the end on the PC side to ensure a transient voltage spike doesn't kill your COM port.
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