The @brightsign/serialport object is implemented by a third party API. See https://serialport.io/docs/9.x.x/ .
Examples
See https://github.com/brightsign/, exposed by the BrightSign OS on the player, allows integration with the player serial port to transmit and receive serial data. This is a serial port binding with support for the third-party Node SerialPort package. See About SerialPort | Node SerialPort for more information.
The @brightsign/serialport binding is used to initialize the serialport object’s underlying communication module through the binding property.
Example
See bs-node-serialport/tree/master: master for a reference implementation.