[aprssig] usb - serial

[Ben Lindner-VK5JFK]

Thanks for that Wes.

Im not actually connecting a TNC at this stage. Its just connecting a 
Davis Wx station to a computer without any serial ports and wanted to 
see if people have had any issues with a usb-serial  setup

cheers
Ben
VK5JFK

Wes Johnston, AI4PX wrote:
> The only problems I've heard of with usb serial adapters are on the 
> transmit side of things.  Many prolific usb adapters won't send a 
> packet out until they see a CR or LF... of course when you are in KISS 
> mode, the packets terminate with $c0, so they usually end up getting 
> sent when the next packets comes along, so they stay one packet 
> behind.  The reason for this I think is that the packet _data_ 
> actually ends with CR, but the packet _frame_ ends with $c0... so the 
> serial adapter sends the packet out when it sees the CR, but that's 
> not enough to make the TNC transmit since the KISS protocol is 
> awaiting for the $c0 that denotes the end of the frame.  So the TNC is 
> essentially sitting on go, waiting for that next $c0 to come along.  
> When the next frame is sent, the data portion of the packet once again 
> ends in CR, the usb serial adapter sends it, and in doing so, the TNC 
> finally gets to see the $c0 it needs to go ahead and TX the previous 
> packet.  Hope this makes sense.
>
> In normal CONVerse TNC mode this isn't a problem since each packet 
> ends with a CR and/or LF.  
>
> I'm not aware of any receiving problems with USB adapters though.
>
> Wes
> ---
> God help those who do not help themselves.
>
>
> On Sat, May 1, 2010 at 17:54, Ben Lindner-VK5JFK <vk5jfk at activ8.net.au 
> <mailto:vk5jfk at activ8.net.au>> wrote:
>
>     Hi All,
>
>     Is anyone using a Vantage Pro2 serial unit with the APRS data
>     logger ( different to standard data logger ) with a USB-Serial cable.
>
>     If so, have you encountered any problems
>
>     cheers
>     Ben
>     VK5JFK
>
>
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