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Question Receive wrong caracters from Serial Port

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I need to communicate with a PLC in serial port. PLC sends 4 possible data: 0, 1, 2 or 3 (which are status).
My vb.net program uses IO.Ports.Serial Port class. When I read the data, the "1" and "2" are good, but the "0" and "3" are received as "?". I tried all the Read method (ReadByte, ReadExisting, Read, etc), it always give the same result. In HyperTerminal, it's fine.

I made a test program in another computer (Win 7). Test was perfect, I received all 4 status correctly. I ran the same test program on the original computer (Win XP) and once again, I got the "1" et the "2" but the "0" and the "3" was "?" (ascii 63).

anyone have an idea?? because I'm really puzzled here.

thanks a lot for your time and help
Dec 15 '11 #1
2 1612
8,435 Recognized Expert Expert
I believe you should post this question in the VB.Net forum. This one's for the (very old) VB 4, 5 and 6, which work quite differently.
Dec 18 '11 #2
8,435 Recognized Expert Expert
P.S. It's not that anyone would refuse to answer your question here, it's just that you may not find people with the right expertise. I'm not familiar with VB.Net at all.
Dec 18 '11 #3

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