Paradyne 4929 DSLAM Network Card User Manual
Contents
1. November 1996 3980 A2 GZ40 20 Table 1 3 of 3 V 42 MNP Buffer Configuration Options for SDC TXBuffDiscDelay 10sec Nxt 10sec Disable 60sec This configuration option only appears when Async Sync Mode is configured for Async and Error Control Mode is not configured for DirectMode or when Async Sync Mode is configured for Sync and Sync Comp Mode is not configured for DirectMode Transmit Buffer Disconnect Delay Determines how long the modem continues to transmit data stored in its Transmit buffer when the modem is commanded to disconnect by a locally attached DTE Disable Modem disconnects immediately without attempting to send data stored in its buffer 10 60 sec Maximum amount of time the modem tries to empty its buffer before disconnecting In both cases 10 sec and 60 sec the modem disconnects much sooner if it can empty its buffer The AT command for TXBuffDiscDelay is S49 n RXBuffDiscDelay 10sec Nxt 10sec Disable 60sec This configuration option only appears when Async Sync Mode is configured for Async and Error Control Mode is not configured for DirectMode or when Async Sync Mode is configured for Sync and Sync Comp Mode is not configured for DirectMode Receive Buffer Disconnect Delay Determines how long the modem continues to send to the DTE data stored in its Receive buffer when the modem is commanded to disconnect by a locally attached DTE or detects a line disconnect Disable Mo2. PARADYNE COMSPHERE 3800P us Modems Synchronous Data Compression Feature Document Number 3980 A2 GZ40 20 November 1996 Overview The Paradyne proprietary Synchronous Data Compression SDC feature allows an increase of throughput in data transmission and has an error correcting procedure so that transmitted data is less sensitive to channel disturbances The ITU T recommendations V 42bis and V 42 have data compression and error correcting EC procedures for DCEs connected to asynchronous DTEs These procedures form the basis of Paradyne s SDC feature With the SDC feature two DTEs can exchange data via a synchronous protocol Figure 1 while the DCE provides the new synchronous data compression and error correction functions Figure 2 The synchronous data from the local DTE after compression is inserted into DCE frames which are sent to the remote DCE Inverse operations then occur at the remote DCE SDC can be used with V 34 and V 32 family modulations on dial or leased lines and in a dial backup or standby mode SDC is available as an installable option beginning with firmware Release 3 0 SYNCHRONOUS PROTOCOL DTE DTE 495 14784 Figure 1 Sample DTE Exchange of Data via Synchronous Protocol and SDC 3980 A2 GZ40 20 November 1996 1 FUNCTION FUNCTION INTERCHANGE SIGNAL CIRCUITS CONVERTER SYNCHRONOUS FUNCTION LINE DTE CONTROL FUNCTION 495 14785 Figure 2 Synchronous Data
3. Compression Installing the SDC Feature The SDC feature can be installed using AT commands or the DCP Installing the SDC Feature Using the DCP To install SDC using the DCP use this procedure 1 Press the gt key until Control appears Press F1 2 Press the gt key until Install appears Press F1 3 If the SDC option is not visible press the gt key until SDC appears NOTE If SDC has been installed on this modem SDC will not appear 4 Press the function key F1 F2 or F3 directly beneath SDC 5 Enter the Product Authorization Code for SDC e Use the and keys to move the cursor to each digit position e Press F2 to increment each digit to the required value The Product Authorization Code for SDC is 011993 6 Once the digits are set to the required values press F1 to select Ent 7 Press the key to go to the top of the menu tree then press the key until Status appears Press F1 8 Press the key until Options appears Press F2 or F3 9 Scroll through the installed options SDC is listed among them 2 November 1996 3980 A2 GZ40 20 10 Perform a power reset e Fora standalone modem turn the Power switch to the Off position then to the ON position or e For a carrier mounted modem release the lock slide the modem part of the way out of the carrier then replace it and lock it in place 11 Set the SDC configuration options suitable for your environment See Tables and 2 Installing th
4. must indicate to the transmitting DTE its temporary inability to accept more data this is flow control Flow control is also required in Buffer mode since the DTE rate and line rate can be different Three methods are used to control the DTE flow e Hardware signal CTS circuit 106 e Transmit clock circuit 114 If the transmit clock is clamped then the DTE stops sending data This method only works when the transmit clock is provided by the modem e Natural flow control Some DTEs can only send a limited number of information frames without any acknowledgment from the remote DTE This number is the acknowledgment window size If the DCE buffers this number of DTE frames it will not receive another DTE frame This is equivalent to the SyncFlowControl configuration option being set to None SDC Negotiation The use of SDC and the values of the associated parameters are negotiated at link establishment via a protocol The three associated parameters have the same meaning as those used for asynchronous data compression e Dictionary size parameter e Maximum string length parameter e Data compression request parameter The SDC Negotiation configuration option determines how two modems connect when one or both modems have SDC enabled Two settings are available in the SDC Negotiation configuration option LAPM_Buffer and LAPM_Discon Table 5 shows the six possible SDC Negotiation configuration scenarios 14 November 1996 3980 A2 G
5. Configure Edit DTE Interface 10 November 1996 3980 A2 GZ40 20 Table 4 2 of 2 S Registers for SDC modem Register has the following values 0 Ignore 1 CRC16 The factory setting is Ignore DCP LCD S Register Description Command Sequence 31 SDC Bit Encoding Configure Edit Determines the type of bit encoding used when transmitting synchronous DTE AEN Buter data Register has the following values 0 NRZ 1 NRZI The factory setting is NRZ S32 SyncDTE CRC Configure Edit Determines whether the CRC of the DTE frame is transmitted from modem to V42 MNE Bufer 3980 A2 GZ40 20 November 1996 11 Synchronous Data Format The SDC feature supports the High level Data Link Control HDLC and Synchronous Data Link Control SDLC type protocols for synchronous DTE data An HDLC frame is composed of an information field containing the data to transmit plus an overhead address control and FCS fields used by the DTE protocol Flags opening and closing the HDLC frame serve as frame delimiters Figure 3 495 14783 Figure 3 Synchronous Data Format A 3800Plus modem with the SDC feature supports DTE frame sizes up to 4300 bytes This conforms to the X 25 recommendation which defines a maximum size of data packets as equal to 4096 bytes If the modem has the SDC Delay Min configuration option set to Rx_Clock there is no limitation on the DTE frame size for the DTE frame
6. If the remote synchronous modem does not have SDC capability then the local connection is made in Buffer mode Link Access Procedure for Modems or Disconnect The modem attempts to establish an SDC connection If the remote modem has SDC capability then the connection is established with SDC active If the remote modem does not have SDC capability then no connection occurs and the modem generates a disconnect The AT command for SDC Negotiation is S28 n See Table 4 page 10 SDC Idle Fill Flag_Fill Nxt Flag_Fill Mark_Fill This configuration option only appears when the Async Sync Mode configuration option is set to Sync and Sync Comp Mode configuration option is not set to DirectMode Synchronous Data Compression Idle Fill Determines whether the modem uses an HDLC flag or mark to fill the time between DTE frame transfers Flag_Fill Causes the modem to fill the time between DTE frame transfers with HDLC flags Mark_Fill Causes the modem to fill the time between DTE frame transfers with marks The AT command for SDC Idle Fill is S29 n See Table 4 page 10 SDC BitEncoding NRZ Nxt NRZ NRZI This configuration option only appears when the Async Sync Mode configuration option is set to Sync and Sync Comp Mode configuration option is not set to DirectMode Synchronous Data Compression Bit Encoding Determines the type of bit encoding scheme NRZ or NRZI the modem uses when transmitting synchronous DTE data NRZ Ca
7. THIS AGREEMENT SUPERSEDES ALL PRIOR ORAL AGREEMENTS PROPOSALS OR UNDERSTANDINGS AND ANY OTHER COMMUNICATIONS BETWEEN US RELATING TO THE SUBJECT MATTER OF THIS AGREEMENT 18 November 1996 3980 A2 GZ40 20
8. U SHOULD READ THE TERMS AND CONDITIONS OF THIS AGREEMENT BEFORE YOU USE THE SOFTWARE ONCE YOU HAVE READ THIS LICENSE AGREEMENT AND AGREE TO ITS TERMS YOU MAY USE THE SOFTWARE BY USING THE SOFTWARE YOU SHOW YOUR ACCEPTANCE OF THE TERMS OF THIS LICENSE AGREEMENT The terms and conditions of this Agreement will apply to the Software supplied herewith and derivatives obtained therefrom including any copy If you have executed a separate written agreement covering the Software supplied herewith such agreement will govern 1 TITLE AND LICENSE GRANT a The Software is copyrighted and or contains proprietary information protected by law All Software and all copies thereof are and will remain the sole property of Paradyne or its suppliers Paradyne hereby grants you a personal non transferable and non exclusive right to use the Software on a single modem Any other use of the Software shall automatically terminate this license b Use of the Software anywhere except in the United States may in addition to the terms and conditions of this License Agreement be subject to the terms and conditions of a separate written agreement signed by the user c You agree to use your best efforts to see that any user of the Software complies with the terms and conditions of this License Agreement and refrains from taking any steps such as reverse assembly or reverse compilation to derive a source code equivalent of the Software d Software and documenta
9. Z40 20 Table 5 SDC Negotiation Configuration Scenarios Originating Modem Answering Modem Negotiation Results SDC enabled with LAPM_Buffer SDC enabled SDC connection negotiation SDC enabled with LAPM_Discon SDC enabled SDC connection negotiation SDC enabled with LAPM_Buffer SDC disabled Buffer mode connection negotiation SDC enabled with LAPM_Discon SDC disabled Disconnect negotiation SDC disabled SDC enabled with LAPM_Buffer negotiation Buffer mode connection SDC disabled SDC enabled with LAPM_Discon negotiation Disconnect If during the negotiation phase the modem with SDC enabled receives data from the remote modem indicating that it has SDC disabled the link will not be established between the two modems For example the link will not be established if the remote modem is configured for Async mode with an EC mode of V42 MNPorBfr V42 MNPorDsc LAPM_Buffer or LAPM_Discon On a leased line the originating modem sends an endless EC negotiation sequence with the SDC request parameter Data cannot be successfully transmitted On a leased line the answering modem waits indefinitely for an EC negotiation sequence with an SDC request parameter Data cannot be successfully transmitted Monitoring SDC Performance If SDC is enabled six performance measurements related to SDC can be displayed on the DCP These measurements are available i
10. ck source is derived from the modem s internal clock This clock is available as an output on Pin 15 TXC of the ElIA 232 D interface External The transmit data s clock source is provided by the DTE on Pin 24 XTXC on the EIA 232 D interface Receive Clock Loop The modem s transmit clock is derived from its received analog signal The derived clock is available as an output on Pin 15 TXC of the ElIA 232 D interface NOTE RXC_Loop does not appear if SDC is enabled NOTE TMp tributaries are forced to RXC_Loop The AT command for Tx Clock Source is amp Xn November 1996 3980 A2 GZ40 20 Table 3 AT Commands for SDC AT DCP LCD Command Description Command Sequence DMn SDC Delay Minimization Configure Edit Minimizes the delay introduced by SDC by allowing the modem to transmit a VARIMNE Buter DTE frame to its DTE in a discontinuous way DMO No delay minimization The modem does not begin transmitting a frame to its DTE until the entire frame has been received DM1 Delay minimization The modem begins to transmit data from a DTE frame to its DTE even if the end of the DTE frame has not yet been received by the modem The factory setting is No Delay Minimization Qn Sync Flow Ctrl Synchronous Flow Control of DTE Configure Edit Controls the type of synchronous data flow control while using data NAME EMI compression Q0 No flow control Q1 Flow control using transmit clock ci
11. dem disconnects immediately without attempting to send data stored in its buffer 10 60 sec Maximum amount of time the modem tries to empty its buffer before disconnecting In both cases 10 sec and 60 sec the modem disconnects much sooner if it can empty its buffer The AT command for RXBuffDiscDelay is S39 n Max Frame Size 256 Nxt 256 192 128 64 32 16 This configuration option only appears when Async Sync Mode is configured for Async and Error Control Mode is not configured for BufferMode or DirectMode or when Async Sync Mode is configured for Sync and Sync Comp Mode is not configured for DirectMode Maximum Frame Size Sets the maximum frame size for V 42 and MNP For MNP operation 64 is the minimum value Any value less than that will automatically default to 64 For cellular applications at least one of the sides should be set to a low value A setting of 32 is recommended Only one modem needs this setting both modems will automatically default to the greatest common value The AT Command for Max Frame Size is An CellularEnhance Disable Nxt Disable Enable This configuration option only appears when Async Sync Mode is configured for Async and Error Control Mode is configured for V42 MNPorBfr V42MNPorDsc LAPM_or_Disc or LAPM_or Bfr or when Async Sync Mode is configured for Sync and Sync Comp Mode is not configured for DirectMode Cellular Enhancement When enabled the modem uses non standard techniques to e
12. e SDC Feature Using AT Commands To install SDC using AT commands use this procedure 1 Attach a DTE to the modem 2 Load the Async Dial factory template e From the DCP select Async Dial from the Factory group of the Configure branch or e If AT commands are enabled enter the AT amp FO command 3 Install the SDC feature Enter the command AT amp amp 112 011993 The modem responds OK 4 Perform a power reset Enter the command ATZ9 5 Check the installed features Enter the command AT amp amp IO The modem responds with a list of features installed in your modem including SDC 6 Set the SDC configuration options suitable for your environment See Tables 3 and 4 Menu Status and Result Codes When SDC is active and the modem is online the top line of the DCP display shows Online mrV42t Leased mrV42t Backup mrV42t or Stndby mrV42t where mr is the modem rate For example Online 33 6V42t is displayed on the DCP of a modem using SDC and connected to a dial line at 33 600 bits per second bps When extended result codes are set to contain the data compression protocol and SDC is active connect messages include the characters V42t For example when a modem with SDC active connects to a dial line at 33 600 bps the result code CONNECT 33600 V 42t RX 33600 TX 33600 is sent to the DTE 3980 A2 GZ40 20 November 1996 3 SDC User Interface When SDC is enabled the following configuration options are available to s
13. et up the SDC feature Some of the configuration options are not displayed unless SDC is enabled V 42 MNP Buffer see Table 1 Sync Comp Mode SDC Negotiation SDC Idle Fill SDC Bit Encoding Sync DTE CRC SDC Delay Min Sync Flow Control TX Buff Disc Delay RX Buff Disc Delay Max Frame Size Cellular Enhance DTE Interface see Table 2 Sync DTE Rate Tx Clock Source November 1996 3980 A2 GZ40 20 Table 1 1 of 3 V 42 MNP Buffer Configuration Options for SDC Sync Comp Mode DirectMode Nxt DirectMode HDLC SDLC This configuration option only appears if Async Sync Mode is configured for Sync Synchronous Compression Mode Enables and disables synchronous data compression DirectMode Disables the Synchronous Data Compression mode HDLC SDLC Enables the Synchronous Data Compression mode The AT command for Sync Comp Mode is SCn See Table 3 page 9 SDC Negotiation LAPM_Buffer Nxt LAPM_Buffer LAPM_Discon This configuration option only appears when the Async Sync Mode configuration option is set to Sync and Sync Comp Mode configuration option is not set to DirectMode Synchronous Data Compression Negotiation Determines the type of negotiation used when the modem attempts to connect using SDC See Table 5 page 15 Link Access Procedure for Modems or Buffer The modem attempts to establish an SDC connection If the remote modem has SDC capability then the connection is established with SDC active
14. frame time fill RX The number of bits per second The ratio between the number of The ratio between the number of bits per second received from the line and the line rate The calculation does not include the DCE interframe time fill Tuning SDC Efficiency SDC efficiency is dependent on the configuration parameters of the DTE and the modem DTE Configuration The way DTE parameters are changed and whether they can be changed depends on your DTE See the documentation that came with your DTE DTE rate configuration parameter The nominal DTE rate the Tx Rx clock s frequency at the DTE DCE interface can be a bottleneck Increase the nominal DTE rate If the DTE rate measurement reported by your modem is close to the nominal DTE rate If the Line Efficiency measurement reported by your modem is substantially less than 100 percent If the ratio between the nominal DTE rate and the line rate is less than the Compression Ratio DTE acknowledgment window size configuration parameter This is the number of information frames the DTE will send without awaiting positive acknowledgment Increase the DTE acknowledgment window size if your modem reports a low DTE rate and a comparatively high Compression Ratio and therefore a Line Efficiency measurement substantially less than 100 percent Set it to the maximum possible value DTE frame size configuration parameter If SDC modems are used between synchronous DTEs then the DCE frame s
15. guration the user can select rates on the DTE DCE line or clock frequencies in the range from 1 2 kHz to 128 kHz When the transmit clock is provided by the DTE the receive clock is set by the modem equal to the DTE clock Figure 4 When SDC is in use the Tx Clock Source configuration option cannot be set to Receiver Clock Loop NOTE When faster speeds are used above 57 6 kHz and the transmit clock is provided by the modem data transmission can be sensitive to DTE cable length and capacitance as well as the DTE s drivers and receivers Should you encounter bit errors related to the above conditions you may want to change the Tx Clock Source configuration option setting to External provided the DTE can support the required transmit clock signal or change the length of the DTE cable XTCLK 113 TXC 114 RXC 115 CLOCK SOURCE 495 14782 Figure 4 Clocks at the DTE DCE Interface 3980 A2 GZ40 20 November 1996 13 Flow Control Method The data transmitted from the DTE is sent to the DCE at a rate determined by the transmit clock frequency When SDC is active this data is then compressed in the DCE and sent to the remote DCE at the line rate less than the rate between the DTE and DCE usually twice three or four times less If the data sent by the DTE is not compressible or bad line conditions cause retransmissions between the two DCEs then the transmitting DCE
16. ize and not the DTE frame size must take into account the line error rate Set the DTE frame size to as large a value as your DTE and your DTE application can handle This reduces the significance of DTE frame overhead and reduces the delay expressed in number of DTE frames for positive acknowledgment 16 November 1996 3980 A2 GZ40 20 Modem Configuration There are also configuration options in the V42 MNP Buffer branch of the 3800Plus modem which affect SDC efficiency LAPM Max Frame Size Except in environments where line impairments are known to be unusually high set this to the maximum 256 Sync DTE CRC If the CRC type of the DTE frame is the 16 bit CRC for HDLC frames as defined by ITU T set this to CRC16 SDC Delay Min If clamping of the receive clock circuit 115 is accepted by your DTE then set this to Rx_Clock Sync Flow Cntrl The Tx_Clock selection is suitable for most synchronous DTEs If your DTE interprets transmit clock clamping or a drop in CTS as a problem resulting in an aborted frame set Sync Flow Cntl to None Selecting None should not be a problem if the entire acknowledgment window of DTE frames does not exceed 5 kilobytes so that it can be buffered by the modem Software License Agreement THIS AGREEMENT CONTAINS THE PARADYNE CORPORATION LIMITED USE SOFTWARE LICENSE TERMS FOR THE SYNCHRONOUS DATA COMPRESSION FEATURE FOR COMSPHERE 3800PLUS MODEMS HEREINAFTER THE SOFTWARE YO
17. n the SDC submenu of the Status branch and are divided into two groups TX transmit measurements and RX receive measurements Call_Setup lt Identity DTE SDC Options ana TX RX 496 14951 3980 A2 GZ40 20 November 1996 15 Both groups have DTE Rate Compression Ratio and Line Efficiency measurements Each measurement is an average of the last ten seconds data and is updated every second See Table 6 Table 6 SDC Performance Measurements sent to the DTE This number takes into account only the data between the opening and closing flags of the HDLC frames Flags and DTE interframe time fill are ignored bits in the output and input of the decompression algorithm The calculation does not include the overhead of the LAPM frame or the DTE flags and DTE interframe time fill Group DTE Rate Compression Ratio Line Efficiency TX The number of bits per second The ratio between the number of The ratio between the number of received from the DTE This bits in the input and output of the bits per second sent on the line number takes into account only compression algorithm The and the line rate The calculation the data between the opening and calculation does not include the does not include the DCE closing flags of the HDLC frames overhead of the LAPM frame or interframe time fill Flags and DTE interframe time fill the DTE flags and DTE are ignored inter
18. nhance V 42 operation for cellular applications It is still compatible however with modems which do not have the cellular enhancement implemented or enabled The AT command for CellularEnhance is S91 n 3980 A2 GZ40 20 November 1996 Table 2 DTE Interface Configuration Options for SDC Sync DTE Rate 128000 Nxt 128000 115200 112000 96000 76800 72000 64000 57600 56000 48000 38400 28800 19200 14400 9600 4800 2400 1200 This configuration option does not appear when e Async Sync Mode configuration option is set to Async e Sync Comp Mode configuration option is set to DirectMode e Tx Clock Source configuration option is set to External e The SDC feature is disabled Synchronous DTE Data Rate Identifies the synchronous DTE s operating rate to the modem Data rates from 128 000 bps to 1200 bps are supported NOTE A cable less than fifty feet in length is required for rates over 19 200 bps Data synchronization at rates over 57 600 bps is sensitive to cable length and capacitance and the DTE s drivers and receivers External transmit clocking may be required The AT command for Sync DTE Rate is S30 n See Table 4 page 10 Tx Clock Source Internal Nxt Internal External RXC_Loop This configuration option only appears when Async Sync Mode is configured for Sync Transmit Clock Source Determines the source of timing for synchronous data transmitted from the DTE Internal The transmit data s clo
19. ot begin transmitting a frame to its DTE until the entire frame has been received Rx_Clock The modem begins to transmit data from a DTE frame to its DTE even if the end of the DTE frame has not yet been received by the modem The receive clock circuit 115 is clamped when the beginning of a DTE frame has been transmitted to the DTE and no other data from this DTE frame has been received by the modem As soon as data from the current DTE frame can be transmitted to the DTE the receive clock is released The Rx_Clock option appears only if the Tx Clock Source configuration option is set to Internal The AT command for SDC Delay Min is DMn See Table 3 page 9 Sync Flow Cntrl None Nxt None Tx_Clock CTS SyncDTE This configuration option only appears when the Async Sync Mode configuration option is set to Sync and Sync Comp Mode configuration option is not set to DirectMode Synchronous Flow Control Controls the type of synchronous data flow control while using data compression None Modem does not control the flow from the synchronous DTE Tx_Clock The transmit clock circuit 114 clamps when the modem is unable to accept supplementary data from the DTE Tx_Clock appears only if the Tx Clock Source configuration option is set to Internal CTS_SyncDTE CTS signal circuit 106 is set to OFF when the modem is unable to accept supplementary data from the DTE The AT command for Sync Flow Cntrl is Qn See Table 3 page 9
20. rcuit 114 Q2 Flow control using CTS circuit 106 The factory setting is No Flow Control SCn Sync Comp Mode Synchronous Compression Mode Configure Edit A V42 MNP Buffer Enables and disables synchronous data compression SCO Disable Synchronous Data Compression mode SC1 Enable Synchronous Data Compression mode The factory setting is Disable 3980 A2 GZ40 20 November 1996 Table 4 1 of 2 S Registers for SDC Identifies the synchronous DTE s operating rate to the modem Register has the following values 0 128 000 bps 1 115 200 bps 2 112 000 bps 3 96 000 bps 4 76 800 bps 5 72 000 bps 6 64 000 bps 7 57 600 bps 8 56 000 bps 9 48 000 bps 10 38 400 bps 11 28 800 bps 12 19 200 bps 13 14 400 bps 14 9600 bps 15 4800 bps 16 2400 bps 17 1200 bps The factory setting is 128 000 bps DCP LCD S Register Description Command Sequence 28 SDC Negotiation Configure Edit Controls negotiation between two modems attempting to connect using SDC Ae NINE EUG Register has the following values 0 LAPM_Buffer 1 LAPM_Discon The factory setting is LAPM_Buffer 29 SDC Idle Fill Configure Edit Determines whether the modem uses an HDLC flag or mark to fill the time SAeMING BUNGE between DTE frame transfers Register has the following values 0 Flag_Fill 1 Mark_Fill The factory setting is Flag_Fill 30 Sync DTE Rate Synchronous DTE Rate
21. s transmitted from the remote modem to this local modem since the whole frame need not be buffered The SyncDTE CRC configuration option determines whether the CRC of the DTE frame the FCS field is transmitted If the CRC type is known to be the 16 bit CRC for HDLC frames as defined by ITU T generator polynomial x 6 x 2 x 1 the CRC can be removed by the local modem and added to the DTE frame by the remote modem SDC Algorithm The compression algorithm is based on V 42bis British Telecom Lempel ZIV BLTZ DTE and DCE Frames Data exchanged between the local and remote DCEs is according to the LAPM protocol The structure of a LAPM frame DCE frame is identical to the HDLC frame The data from the DTE is compressed into the information field of the DCE frame After compression one DTE frame is segmented into one or several DCE frames 12 November 1996 3980 A2 GZ40 20 Data Synchronization Data exchanged between the synchronous DTE and the modem is synchronized by two clock signals Data coming from the DTE is synchronized by the transmit clock and data received by the DTE is synchronized by the receive clock The transmit clock is provided by the modem on circuit 114 or by the synchronous DTE on circuit 113 The receive clock is provided by the modem on circuit 115 When the transmit clock is provided by the modem the transmit and receive clocks are locked on the same clock source internal to the modem In this confi
22. tion copyright 1996 Paradyne 3980 A2 GZ40 20 November 1996 17 SOFTWARE USE a The Software 1 shall be disabled or deleted when no longer used in accordance with this License Agreement or when the right to use the software is terminated and 2 shall not be removed from a country in which use is licensed TERM This license is effective until terminated You may terminate it at any time by destroying the documentation and requesting that Paradyne disable or delete the Software on your modem It will also terminate automatically if you fail to comply with any of the terms and conditions of this Agreement LIMITATION OF LIABILITIES a Paradyne has used reasonable efforts to minimize defects and errors in the Software However you assume the risk of any and all damage or loss from use or inability to use the software b Unless a separate agreement for software support is entered into between you and Paradyne Paradyne bears no responsibility for supplying assistance for fixing errors or for communicating known errors to you pertaining to the Software CHARGES AND USE YOU ACKNOWLEDGE THAT YOU HAVE READ THIS AGREEMENT AND UNDERSTAND IT AND THAT BY USING THE SOFTWARE YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS HEREIN YOU FURTHER AGREE THAT EXCEPT FOR ANY SEPARATE WRITTEN AGREEMENTS BETWEEN PARADYNE AND YOU THIS AGREEMENT IS THE COMPLETE AND EXCLUSIVE STATEMENT OF THE RIGHTS AND LIABILITIES OF THE PARTIES
23. uses the modem to use the standard Non Return to Zero bit encoding scheme NRZI Causes the modem to use the Non Return to Zero Inverted bit encoding scheme The AT command for SDC Bit Encoding is S31 n See Table 4 page 11 3980 A2 GZ40 20 November 1996 Table 1 2 of 3 V 42 MNP Buffer Configuration Options for SDC SyncDTE CRC Ignore Nxt Ignore CRC16 This configuration option only appears when the Async Sync Mode configuration option is set to Sync and Sync Comp Mode configuration option is not set to DirectMode Synchronous DTE CRC Determines whether the CRC of the DTE frame is transmitted from modem to modem Ignore No assumption is made about the CRC type The CRC is transmitted along with the other data in the frame CRC16 The CRC is known to be the 16 bit CRC for HDLC frames defined by ITU T generator polynomial x16 x12 x5 1 Itis removed from the DTE frame by the sending modem and added to the DTE frame by the receiving modem The AT command for SyncDTE CRC is S32 n See Table 4 page 11 SDC Delay Min Off Nxt Off Rx_Clock This configuration option only appears when the Async Sync Mode configuration option is set to Sync and Sync Comp Mode configuration option is not set to DirectMode Synchronous Data Compression Delay Minimization Allows the modem to transmit a DTE frame to its DTE ina discontinuous way to minimize the delay introduced by SDC processing Off The modem does n
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