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Serial connection problem

I am having problems connecting to the BT2S from Hyperterminal. First off, I am running Windows 7 64 bit. As Windows 7 does not include Hyperterminal, I found (by Google) that the hyperterm.exe and hyperterm.dll files could be copied from an XP machine to the 7 machine. I am using a Belkin F5U409 USB to serial adapter. I found drivers for this to make it work on Win 7 64 bit. The combination of Hyperterminal and the Belkin adapter *seems* to function just fine. The Belkin adapter has 3 led’s – usb link, transmit, and receive. Per the Belkin documentation, pin 2 is receive and pin 3 is transmit. I connected transmit of the BT2S to receive of the Belkin adapter and receive to transmit.

When I power on the BT2S, the red led is off. I then connect with Hyperterminal (9600, N, 8, 1, no flow control). I also have local echo turned on. After copying and pasting “AT”, I see the red TX led flash briefly on the Belkin adapter but do not see an “OK” response from the BT2S nor do I see the RX led on the Belkin flash. The red led on the BT2S DOES start flashing though after this. This is as far as I have gotten. Any ideas?

PS. I have Bluetooth disabled on my Android phone to make sure it is not paired.

4 Answers


As you said Hyperterminal isn’t something that comes with windows anymore, so it may be advisable to use Teraterm instead. I have had very good luck with Teraterm and the Virtuabotix BT2S.

The Belkin adapter looks like it should work with the Virtuabotix BT2S Slave or Master based on the 3.3 and 5 volt IO levels, but I haven’t encountered anyone else who has tried it yet so it may require a little work to get going.

The key thing to check is if your transmit on the Belkin side is connected to the receive on the Virtuabotix BT2S Slave side, and that the Receive on the Belkin is connected to the Transmit on the BT2S. The other common mistake is not connecting the ground to the ground (even if you have it powered externally).

Finally you want to make sure that you are pasting the commands in, if you try to type them by hand they will often be entered too slowly for the BT2S to realize it is a command. Let me know how things go, and feel free to message me, or send me a support ticket if this doesn’t help you get things resolved.

An alternative method is to use the Versalino FTDI which has a built in Virtuabotix BT2S port to make the process much easier.


John got back to me and gave me a scope shot of the output from his Belkin USB to Serial, apparently the actual IO levels are -5 Volts to +10 Volts, which explains the problems he encountered.


Note the height of the datalevels

Above is a shot of the Transmit line from the Belkin USB to Serial


John asked if his Virtuabotix BT2S Slave might have been damaged by the IO levels, and will let us know once he picks up the Versalino FTDI to test it out. In general if your LED does not blink when you plug it in, there may be an issue with your device, so it is a distinct possability that the board was damaged by the high voltage levels present on the data lines of the Belkin.


Good news.  I got the Versalino board and was able to connect via Tera Term to change the name and baud rate.  Next step is interfacing it to my embedded Freescale processor.  Thanks!


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