C代码通过linux中的蓝牙串口配置文件从nonin Pulse Oximeter设备读取数据

I am trying to communicate to the Nonin Pulse oximeter device to read the data (Pulse rate and SPO2 level) via Bluetooth. Nonin device supports SPP and HDP profile. I want to communicate through SPP profile. I am able to scan and pair with the device by the sample code available in Bluez. Please tell me next steps how to send command and read data from the device. I have got struck at this point.I am trying to communicate to the Nonin Pulse o