1º Have the latest version of the 24661 interface drivers. Download and unzip.
or
https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers?tab=downloads
2º Go to device manager and select the corresponding COM port with the right button properties (It is recommended that the COM port has no more than 1 digit).
3º Check that the baud rate is correct according to the device that will be the interface.
-Connection with ACPLUS control unit ref. 4410. Baud rate of 38400.
-Connection with MDS control unit ref. 2405 or 24050. Baud rate of 9600.
-Connection with CITY/SKYLINE 6992/7440 readers. 9600 baud rate.
-Connection with CITY Desfire 6957 readers. Baud rate of 9600.
-Connection with CITY fingerprint readers ref. 9781. Baud rate of 11500.