Protocol states

Last Updated : May 07, 2014 |
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The following table summarizes the protocols used at various points in the data transmission stream. See also the figure.
Pulse Code Modulated is known as PCM and Digital Multiplexed Interface is known as DMI.
Protocol states for data communication
Transmission type
Incoming DTE to DCE
OSI layer
Protocols DTE to DCE
DCE to system port
Inside system
Analog
Modem
1
RS-232, RS-449, or V.35
analog
PCM
2
8- or 10-bit code
Voice-grade data
Voice-grade data
ADU
1
RS-232
ADU proprietary
Raw bits
2
Asynchronous 8-bit code
Asynchronous 8-bit code
DMI
Digital
Data Module
1
RS-232, RS-449, or V.35
DCP or BRI
Raw bits
2
8-bit code
DMI
DMI
Digital Signal Level 1 (DS1)
1
Any
DS1
PCM or raw bits
2
8-bit code
DMI or voice- grade data
DMI or voice-grade data
The physical-layer protocol and the DMI mode used in the connection are dependent upon the type of 8-bit code used at Layer 2 between the DTE and DCE equipment, as listed in the table and the table.
Physical-layer protocol versus character code
Protocol
Code
RS-232
Asynchronous 8-bit ASCII, and synchronous
RS-449
Asynchronous 8-bit ASCII, and synchronous
V.35
Synchronous
DMI mode versus character code
DMI Mode
Code
0
Synchronous (64 kbps)
1
Synchronous (56 kbps)
2
Asynchronous 8-bit ASCII (up to 19.2 kbps), and synchronous
3
Asynchronous 8-bit ASCII, and private proprietary