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ImpathNetworks
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Inconsistent Data Transfer ...
« on: Apr 12th, 2010, 10:50am »		 Quote Quote Modify Modify
I just created a virtual comm port (COM2) to send RAW data to my simple Python program. It just dumps whatever traffic it gets from a socket.
 
Then I open HyperTerminal and connect to COM2. COM2 is hard set to 9600, 8, N, 1 ... Hyperterminal is set the same. But every 3rd, 4th character that comes through is garbled. It's almost as if the parity bits are off.  
 
I can just tap 'a', 'a', 'a', etc. and I'll get 'a', 'a', 'ß', etc. (note the last character).  
 
If I attempt the same thing using the TCP/IP (WinSock) option in HyperTerminal the characters go through clean.  
 
Protocol is Raw Data (no preset signals on).
I've tried it with Bitrate Emulation on and off ... no difference.  
I've tried it with Fixed Baud/Control/Flow set and unset ... no difference.
 
Why is my data so flaky using your virtual comm port?
 
 
 
 
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ImpathNetworks
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Re: Inconsistent Data Transfer ...
« Reply #1 on: Apr 12th, 2010, 10:59am »		 Quote Quote Modify Modify
I changed my program to dump the ASCII (in dec and hex) of the data stream and the 8th bit is definitely getting set randomly:  
 
a 97 61
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
ß 225 E1
a 97 61
q 113 71
q 113 71
± 241 F1
q 113 71
± 241 F1
q 113 71
± 241 F1
q 113 71
 
Why would this be?
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Alex_Webster
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Re: Inconsistent Data Transfer ...
« Reply #2 on: Apr 13th, 2010, 6:07am »		 Quote Quote Modify Modify
It's not "Serial Port Redirector" that causes the issue. It's hyperterminal's fault. You can prove it be monitoring the redirector's virtual COM port by portmon tool (http://download.sysinternals.com/Files/PortMon.zip) while quering the virtual COM port by any communication software. You'll see that the data flow is ok.
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ImpathNetworks
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Re: Inconsistent Data Transfer ...
« Reply #3 on: Apr 13th, 2010, 6:17am »		 Quote Quote Modify Modify
So, why does HyperTerminal work when I use the TCP option?
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Alex_Webster
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Re: Inconsistent Data Transfer ...
« Reply #4 on: Apr 13th, 2010, 6:51am »		 Quote Quote Modify Modify
I cannot tell you why Hyperterminal works this way. But you can also use "Serial Port Control" (http://www.fabulatech.com/serial-port-control.html) to write the data to the virtual COM port of Serial Port Redirector.
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