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Why are there two COM ports after connecting the Bluetooth HC-05 module to my PC running on WIN10?

See this image from device manager:

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For sending data I use only one of them but I have to check it before which is correct. I have no idea what the second is used for.

Any idea?

scooterman
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  • This question would get a better, faster answer on [the Arduino forums](https://forum.arduino.cc) – Rojo Mar 29 '21 at 15:35
  • One COM port *might* be RX while the other *might* be TX – Rojo Mar 29 '21 at 15:37
  • @Rojo: I've tested that and it doesn't look like RX/TX because I can both send and receive data on one of those ports. –  Mar 30 '21 at 10:47

1 Answers1

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This answer in Microsoft Technet sounds good:

  • when connecting your terminal program to the first you are actually instructing Windows to attempt to establish the Bluetooth connection to the remote paired device, and if the connection is established the RFCOMM channel will be opened for the exchange of data

  • when connecting your terminal program to the second you are actually instructing Windows to load the SPP SDP record and to remain waiting for incoming connections from the remote paired device.

Sohail
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