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Multiple serial port use in VB5

Multiple serial port use in VB5

Multiple serial port use in VB5

I have an application that uses serial ports (via an IO Networks Edgeport/4 4-port serial hub) to talk to HF radios. If I run my application as 2 instances (either in VB or as .EXE files) and direct one appl. to talk to COM10 and the 2nd one to talk to COM12 and if I start the one that talks to COM10 first.....I see the appl. that talks to COM12 cath up and overtake the COM10 appl. !!

Both radios are being downloaded the exact same data to initialize them. Has anyone else used multiple serial ports and noticed difference in speeds of one port vs another ?? It is possible, of course, that the USB box is causing this. I am checking this out with IO Networks,

RE: Multiple serial port use in VB5

IO Networks believe that they are not the cause of this problem. One test that I ran this morning was to run the code outside of VB5, i.e. by clicking on the shortcut twice and using COM10 on one and COM12 on the other. In this test, COM12 was NOT any faster than COM10 in initializing. Seems that maybe the VB5 IDE environment is causing the difference in speed ???

RE: Multiple serial port use in VB5

The best "suspect" here is WIN95 task dispatching. From hunting around, I am going to try a test that minimizes both windows (or possibly that selects the 1st window after firing up the 2nd application and see what difference it makes. More later.

RE: Multiple serial port use in VB5

Well, WIN95 gives much more priority to the active window. So, if I open a notepad session and then fire up both apps that talk to the radios, then select the notepad session - both apps initialize at the same speed. If I select one app or the other as the active window, it runs faster. I don't know what the algorithm is but obviously favors the active window heavily.

RE: Multiple serial port use in VB5


In NT there's an option to give foreground apps priority - is there somthing similar in w95? Sorry I can't be more specific but I'm a Unix/NT person.


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