vb com port settings

Posted on 2006-11-08
Last Modified: 2010-04-30
I am writing a vb application that uses com ports.
For some reason I get some errors when I run it.
Not vb errors, but I was getting the wrong responses from the device
I was talking to.

When I go to my control panel->System->device manager->Com Port->Port Settings->Advanced
Then I slide the 2 sliders all the way to the left the program works.

Is there any way to make this setting programmatically?
Question by:jackjohnson44
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LVL 76

Accepted Solution

GrahamSkan earned 500 total points
ID: 17900520
Are you using MSComm control?

There is a settings property

    ' Use COM1.
     MSComm1.CommPort = 1
     ' 9600 baud, no parity, 8 data, and 1 stop bit.
     MSComm1.Settings = "9600,N,8,1"

Author Comment

ID: 17900695
I am using those settings.

Check the control panel setting to see what I am talking about.
LVL 76

Expert Comment

ID: 17900820
What sort of flow control are you using? How are you servicing the VB buffers? Are you getting problems on both send and receive?
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Author Comment

ID: 17900945
The problem only happens after running it a few hundred times.

I am not getting errors, I ask it a question and it gives me strange responses.

Either way, the setting seems to work.

Any idea how to change this setting programmatically?
LVL 76

Expert Comment

ID: 17901091
Sorry, No. I guess that you might be able to use use a driver API, but I'm not into it.

This may help you to get an overview.
LVL 26

Expert Comment

ID: 17913698
The data may not come back in one shot. You need to read all data to determine whether the data is received

Show us your MSComm1_OnComm() routine

Author Comment

ID: 17914422
I am specifically asking how to programmatically set the slider that I mention above.

Please do not give alternatives, it is too late to change code.
LVL 26

Expert Comment

ID: 17914483
I think the problem lies on your MSComm1_OnComm() routine. When you increase to highest performance means you will get all data back in one shot. Which implies you do not handle received data correctly

Author Comment

ID: 17914529
That is not the problem, the problem seems to be that my computer is not sending the commands exactly when I want, I think it might save them up sometimes.  If I send one command, I might have to wait to send the next.  I think they are both being sent really close together and my wait is being ignored. The machine I talk to gets confised.  Reguardless of the problem, the way I got around it was playing with this setting.  It has already been tested and agreed upon.  Instead of putting it in the release notes, I want to set it myself.  This is the only thing I am interested in.  Thanks for your help, but I am only looking to change this setting.

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