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

9

10

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