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VB Forum / COM / August 2004MSComm Error 8021 with desc.: "Application-defined or object-defined error"
Can someone tell me the possible causes of the error I have? I have the error 8021 (Application-defined or object-defined error) in a Sub that contains the line FrmMain.MSComm1.Output = (Q$) where Q$ is a string we send on Com1. It contains some other lines, but it only assign a variable to the value 5 and set an Image visible and another image invisible. In the current circumstance, I suppose the error 8021 is caused by MSComm control. The description of the error 8021 for MSComm control is "Internal error retrieving device control block for the port". So what could be the causes of this "Internal error retrieving device control block for the port"? Note: The error happens on our client's computer but we can't reproduce the trouble on our computer and it seems to work properly here. I use Visual Basic 6.0. Thank you!  SignatureMy E-mail: rinouellotravail@globetrotter.net Please CROSSPOST instead of MULTIPOSTing. That way, all answers show in all groups in the list instead of having a separate set of answers in each group. SignatureKen Halter - MS-MVP-VB - http://www.vbsight.com Please keep all discussions in the groups.. With that information it's hard to say. ComDCBError happens when windows can't read the port state. First, make sure it is open: MSComm1.PortOpen = True Catch any excpetions here. Also don't foget to close it in the end, by setting it to False. Next, check the port settings. It could be caused by an unsupported baud rate. I usually test the settings in HyperTerminal first and only then use them in the application. This URL may also help: http://www.mev.co.uk/vbbaud.htm # rcc Hi, The only time that I have heard of this error was associated with a faulty USB serial converter device driver. A driver update was required from the USB device manufacturer. Other virtual serial port devices might cause a similar problem (requiring a similar solution). Dick SignatureRichard Grier (Microsoft Visual Basic MVP) See www.hardandsoftware.net for contact information. Author of Visual Basic Programmer's Guide to Serial Communications, 3rd Edition ISBN 1-890422-27-4 (391 pages) published February 2002. I forgot to tell you the following details: -The word client, here, means a person which is a client of our company. -I use : Windows 2000 Professionnal Service Pack 4 (to develop the application using Visual Basic 6.0 Professional Edition) -Our client use : Windows XP (to run the .exe I made with Visual Basic) Thank you for your answers |
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