Find COM ports

I got an old device that needs to be connected to a COM port.
I tried to conect it to all USB ports, but communication always fails.

On the device (it's a blood pressure measurement device and I want to download the stored data) the is a PC symbol as soon as I put in the plugs.

However, the communication doesn't work.

Only errror message: An error happened during data transmission. 

The manual doesn't talk about com ports, only about USB features.

Anybody, who can help me to find the right USB adaptor? 

Joe