In case the device is in master mode, use a protocol described in the Nano Online Quick Start Guide. Please, check pages 29 and 30 for the detailed instructions on setting up an HTTP POST request and response. The response defines USER_INTERFACE_SIGNAL according to the COM protocol.
Also, check our PHP script with an example for HTTP POST response in master mode.
It is possible to preset the device behavior, including the buzzer sound, by sending the direct command to the reader from the software you currently use, or you can use some of our SDK tools (recommended: uFR Shell Environment and µFR Readers Tool).
For the details of the commands, please download the µFR Series API (check the ReaderUISignal function on page 42).