Spy on comm port using VB

I would like to spy (peek, sniff, capture, redirect) data sent to a comm (RS232) port from an existing application that cannot be modified for purposes of modifying that information into a new data stream for export to another RS323 port. I have a navigation program that sends out  tracking information through an RS232 port using the newer NMEA 0183 protocal. I would like to modify this data to an older NMEA 0180 protocal so that my vintage auto pilot will accept it. I am looking for a VB 6.0 preferrable application. the application cannot interfere with the communications, it should only be able to read the data being sent out the RS232 port.
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Erick37Connect With a Mentor Commented:
Right, device drivers aren't written in VB (thank God).  I'm suggesting finding a (shareware or cheapware) utility which will allow the data from one virtual port to be directed to another virtual port.  If the existing application allows the user to select comm5 for example, this should work.

another example:
Virtual Serial Ports Driver XP 4.5
Need an extra port for this.
Connect two ports whit a null modem cable. One of these would be the formal output. Then you can set up two MS Comm controls in VB app and get access to data in middle and send it to third port after modifications.


VincentpirainoAuthor Commented:
Unfortunately, this and many newer laptops are coming without any RS232 ports; I need a non-hardware dependant solution, thank you for your post Matti.
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If your existing application allows you to select a serial port, then you could use a virtual serial port driver to redirect the data to your application (in theory).  These are third party drivers and it seems there are many out there, some costing more than others.

Here is one example:

Hope it helps!

Won't found these on VB
Here is on but it's developed on Win2000 DDK and VC++


It's GPL opensource, not a demo.

VincentpirainoAuthor Commented:
Erick37, thanks for your solution, not exactly what I was looking for but it will work, solutions range $69-$99 and come with their own SDK, pretty neat, thanks.
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