Patton electronic 275, 2715 MULTIFRAMEG.704, CRC-4 MF, Unframed G.703 SW3 SW4, Clock Modes

Switch SW2: CAS Multiframe

The Channel Associated Signaling (CAS) multiframe uses Timeslot 16 (TS16) to send multiframe (MF) alignment data. In CAS MF, a multi- frame is defined as 16 frames, where a frame consists of 32 64kb/s timeslots, numbered 0 to 31. TS16 of the first frame in the MF contains the CAS MF alignment word in the upper four bits. The alignment word is always 0000 (binary). The 2715 does not perform any signaling in TS16 other than to insert the MF alignment word, in order to maintain MF alignment. When CAS MF disabled, the unit transmits user data in TS16; therefore, up to 31 channels are available for user data. When it is enabled, TS16 is not available to the user. In this case, the user can use up to 30 channels for data. CAS MF can be used with CRC-4 MF or by itself. When enabled, both units must employ CAS MF; if one unit is set for CAS MF, and the other is not, the one using CAS MF will detect a loss of sync.

SW2	Option
Off	Disabled
On	Enabled

Switch SW3 & SW4: CRC-4 Multiframe/Clock mode

In framed mode, SW3 is used for CRC-4 MF. CRC-4 Multiframe uses Time Slot zero to carry CRC-4 information. It operates independently of CAS MF. When CRC-4 is enabled, the unit monitors the incoming data stream for CRC-4 errors. It transmits CRC-4 error counts to the trans- mitting unit. Excessive errors may cause loss of frame or loss of sync. If CRC-4 MF is used, both units must be set for set for CRC-4 MF. Otherwise, the one using CRC-4 MF will detect loss of sync.

In unframed mode, SW3 is used to along with SW4 to determine the clock mode. In unframed mode, the model 2715 can be set to network, internal or external clock mode. This is done by setting both SW3 and SW4 to the on position.

In framed mode SW4 is used alone to determine the 2715 transmitter timing. The 2715 can be set to Network or Internal clock.

The following charts represent both cases.

	MULTIFRAME(G.704)
SW3	CRC-4 MF	SW4	Clock Mode
On	On	Off	Network
Off	Off	On	Internal

UNFRAMED (G.703)

SW3	SW4	Clock Mode
Off	Off	Network (Default)
Off	On	Internal
On	On	External
On	Off	Network

CLOCK MODES

Network Clock Transmitter timing is derived from the received line signal.

Internal Clock Transmitter clock is derived from an internal clock source.

External Clock Transmitter timing is derived from the local DTE device. Valid only in unframed mode.

Note: When using the 2715 as a high-speed short range modem, one unit of the link must be configured in either internal or external clock, and the other end must be configured for network clock mode.

Switches SW5, SW6, SW7, and SW8

Use Switches SW5, SW6, SW7, and SW8 to set the DTE data rate.

SW5	SW6	SW7	SW8	Speed
Off	Off	Off	Off	Clear Channel (2.048Mbps)
On	Off	Off	Off	64kbps
Off	On	Off	Off	128kbps
On	On	Off	Off	192kbps
Off	Off	On	Off	256kbps
On	Off	On	Off	384kbps
Off	On	On	Off	512kbps
On	On	On	Off	640kbps
Off	Off	Off	On	768kbps
On	Off	Off	On	1024kbps
Off	On	Off	On	1280kbps
On	On	Off	On	1536kbps
Off	Off	On	On	1600kbps
On	Off	On	On	1920kbps
Off	On	On	On	1984kbps
On	On	On	On	invalid

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