Introduction

RFCOMM provides an emulation of serial cable line settings and status of an RS-232 serial port. RFCOMM is a simple transport protocol over L2CAP. So the protocol could supports up to 60 simultaneous connections between two Bluetooth devices.(The number
of connections that may be used simultaneously in a Bluetooth device depends on the implementation). It does not have any ability to correct errors. The reliability relies on Bluetooth baseband.(RFCOMM‘s flow control also uses the basband‘s capabilities.)

RFCOMM data rate is not configurable with the typical baud rate, e.g. 19200. RFCOMM will transfer the data as fast as it can. The actual data rate will vary, and what the highest data rate is  can be a complicated issue.(see the previous article <How
Fast is Bluetooth>) RFCOMM data rates will be limited in devices where there is a physical serial port involved. Implementations may optionally pace data on virtual serial ports.

(be continued...)