In a bluetooth connection between Android phone and health device which one is the master device? The health device is Omron Bluetooth Blood Pressure Monitor. The bluetooth profile can be either Serial Port Profile (SPP) or Health Device Profile (HDP).

I'm writing an Android app to read information from the health information from the health device.
Android's documentations only mention client and server relationship so it's more important to determine which device is the client and which is the server. The device that initiates the connection is the client while the other is server.

Someone says that the master is usually the client while the slave is the server but I'm not sure if that applies for all cases.