Part F:1
RFCOMM with TS 07.10
Serial Port Emulation
This document specifies the RFCOMM proto-
col by specifying a subset of the ETSI TS 07.10
standard, along with some Bluetooth-specific
adaptations
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CONTENTS
1 Introduction ......................................................................................399
1.1 Overview ..................................................................................399
1.2 Device Types ...........................................................................399
1.3 Byte Ordering...........................................................................400
2 RFCOMM Service Overview ............................................................401
2.1 RS-232 Control Signals............................................................401
2.2 Null Modem Emulation.............................................................402
2.3 Multiple Emulated Serial Ports .................................................403
2.3.1 Multiple Emulated Serial Ports between two Devices .403
2.3.2 Multiple Emulated Serial Ports and Multiple Bluetooth
Devices403
3 Service Interface Description..........................................................405
3.1 Service Definition Model ..........................................................405
4 TS 07.10 Subset Supported by RFCOMM ......................................406
4.1 Options and Modes..................................................................406
4.2 Frame Types ............................................................................406
4.3 Commands...............................................................................406
4.4 Convergence Layers................................................................407
5 TS 07.10 Adaptations for RFCOMM ................................................408
5.1 Media Adaptation .....................................................................408
5.1.1 FCS calculation ...........................................................408
5.1.2 P/F-Bit(Erratum 1053) .................................................408
5.1.3 CR bit(Erratum 1510) ..................................................409
5.2 TS 07.10 Multiplexer Start-up and Closedown Procedure .......410
5.2.1 Start-up procedure.......................................................410
5.2.2 Close-down procedure ................................................410
5.2.3 Link loss handling........................................................411
5.3 System Parameters..................................................................412
5.4 DLCI allocation with RFCOMM server channels......................413
5.5 Multiplexer Control Commands................................................414
5.5.1 Remote Port Negotiation Command (RPN) ................414
5.5.2 Remote Line Status Command (RLS) .........................415
5.5.3 DLC parameter negotiation (PN).................................415
6 Flow Control .....................................................................................417
6.1 L2CAP Flow Control in Overview.............................................417
6.2 Wired Serial Port Flow Control.................................................417
6.3 (Erratum 1549)GSM TS 07.10 Flow Control............................417
6.4 Port Emulation Entity Serial Flow Control ................................419
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6.5 Credit based flow control(Erratum 1053) .................................420
6.5.1 Initial DLC Negotiation(Erratum1053) .........................420
6.5.2 DLC Operation(Erratum1053).....................................420
6.5.3 Other flow control aspects(Erratum1053) ...................421
7 Interaction with Other Entities........................................................422
7.1 Port Emulation and Port Proxy Entities....................................422
7.1.1 Port Emulation Entity...................................................422
7.1.2 Port Proxy Entity .........................................................422
7.2 Service Registration and Discovery.........................................422
7.3 Lower Layer Dependencies .....................................................424
7.3.1 Reliability.....................................................................424
7.3.2 Low power modes.......................................................424
8 References........................................................................................425
9 Terms and Abbreviations ................................................................426
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1 INTRODUCTION
The RFCOMM protocol provides emulation of serial ports over the L2CAP pro-
tocol. The protocol is based on the ETSI standard TS 07.10. This document
does not contain a complete specification. Instead, references are made to the
relevant parts of the TS 07.10 standard. Only a subset of the TS 07.10 stan-
dard is used, and some adaptations of the protocol are specified in this docu-
ment. Furthermore, an RFCOMM - specific extension is added, in the form of a
mandatory credit based flow control scheme.
1.1 OVERVIEW
RFCOMM is a simple transport protocol, with additional provisions for emulat-
ing the 9 circuits of RS-232 (EIATIA-232-E) serial ports.
The RFCOMM protocol supports up to 60 simultaneous connections between
two Bluetooth devices. The number of connections that can be used simulta-
neously in a Bluetooth device is implementation-specific.
1.2 DEVICE TYPES
For the purposes of RFCOMM, a complete communication path involves two
applications running on different devices (the communication endpoints) with a
communication segment between them. Figure 1.1 shows the complete com-
munication path. (In this context, the term application may mean other things
than end-user application; e.g. higher layer protocols or other services acting
on behalf of end-user applications.)
Figure 1.1: RFCOMM Communication Segment
RFCOMM is intended to cover applications that make use of the serial ports of
the devices in which they reside. In the simple configuration, the communica-
tion segment is a Bluetooth link from one device to another (direct connect),
see Figure 1.2. Where the communication segment is another network, Blue-
tooth wireless technology is used for the path between the device and a net-
work connection device like a modem. RFCOMM is only concerned with the
connection between the devices in the direct connect case, or between the
device and a modem in the network case. RFCOMM can support other config-
urations, such as modules that communicate via Bluetooth wireless technology
on one side and provide a wired interface on the other side, as shown in Figure
Application
Device A
Application
Device B
Communication
Segment
