Fax Modem (250-3581) S Registers Continued Faxback Doc. # 5877 Continued from Faxback Document # 5876 S23 BIT MAPPED OPTIONS Indicates the status of command options. DEFAULT: 103 Bit 0 0 = AT&T5 1 = AT&T4 Bit 1,2,3, - Local DTE Rate 0 = 0 - 300 bps 1 = 600 bps 2 = 1200 bps 3 = 2400 bps 4 = 4800 bps 5 = 9600 bps Bit 4,5 Parity Option 0 = even 1 = not used 2 = odd 3 = none Bit 6,7 0 = AT&G0 1 = AT&G1 2 = AT&G2 S24 RESERVED S25 DELAY TO DTR Register S25 serves two purpose. When the FAX Modem is operation in synchronous mode 1 or 4, the value assigned to S25 specifies the length of time the FAX Modem waits after a connection has been made before examining DTR. This allows the FAX Modem to ignore an ON-to-OFF transition of DTR giving the user sufficient time to disconnect the FAX Modem from the asynchronous terminal and attach it to a synchronous terminal, without forcing the FAX Modem back to the asynchronous command mode. During this time, the value for S25 is read in seconds. (e.g., the factory-set value of 5 equals 5 seconds instead of 0.05 seconds). In all other modes, and after call establishment in synchronous modes 1 and 4, the value is read in 1/100 seconds. In any mode, a change in DTR (ON or OFF) that persists for a period shorter than the value held in S25 is ignored by the FAX Modem while it is in data mode. RANGE: 0-255 (0.01 seconds if mode 1 or 4 when in data mode, 1 second otherwise). S26 RTS TO CTS DELAY INTERVAL Pertains to synchronous operation only. When CTS tracks RTS (AT&RO) and the FAX Modem detects an ON-to-OFF transition on RTS, this register sets the time delay before the FAX Modem turns CTS ON. RANGE: 0-255 hundredths of a second. S27 BIT MAPPED OPTIONS Indicates the status of command options Default: 73 Bit 0,1,3 0 = AT&Q0 1 = AT&Q1 2 = AT&Q3 3 = AT&Q4 4 = AT&Q5 6 = AT&Q6 7 = AT&Q7 Bit 2 0 = AT&L0 1 = AT&L1 Bit 4,5 0 = AT&X0 1 = AT&X1 2 = AT&X2 Bit 6 0 = ATB0 1 = ATB1 Bit 7 = Reserved S28-29 Reserved S30 Inactivity Timer Determines the length of time, in ten-second intervals, that the FAX Modem will wait before disconnection when no data is sent or received. In MNP or V.42 mode, any data transmitted will reset the timer. In other modes, any data transmitted will reset the timer. The inactivity timer is inoperative in synchronous mode. Range: 0-255 Default: 0 (disable) S31-35 Reserved S36 NEGOTIATION FAILURE TREATMENT This register is read when the S48 register contains the value 128 or if an attempted error correction link fails. These fallback options are initiated immediately upon connection if S48=128. Default: 7 The S36 actions are: S36= 0 FAX Modem disconnects S36= 1 FAX Modem stays on-line and a Direct mode connection is established. S36= 2 Reserved S36= 3 FAX Modem stays on-line and a Normal mode connection is established. S36= 4 An MNP connection is attempted and if it fails, the FAX Modem disconnects. S36= 5 An MNP connection is attempted and if it fails, a Direct Mode connection is established. S36= 6 Reserved S36= 7 An MNP connection is attempted and if it fails, a Normal mode connection is established. S37 DISIRED TELCO LINE SPEED This register determines the desired telco line speed if the ATNO command is in effect. Range: 0-7 If an invalid number is entered, the number is accepted into the register, but S37 will act as if the default value is entered. S37 = 0 Attempt to connect at speed of last AT command issued. For DTE speeds greater than 2400 bps, the FAX Modem will attempt to connect at 2400 bps. S37 = 1~3 Attempt to connect at 300 bps. S37 = 4 Reserved. S37 = 5 Attempt to connect at 1200 bps. S37 = 6 Attempt to connect at 2400 bps. S37 = 7 Attempt to connect in V.23 75/1200 mode. S38 DELAY BEFORE FORCED DISCONNECT (ERROR CORRECTION MODE ONLY) This register specifies the delay between the FAX Modem's receipt of the ATH command to disconnect (or ON-to-OFF transition of DTR if the FAX Modem is programmed to follow the signal) and the disconnect operation. For an error-correction connection, this register can be used to ensure that data in the FAX Modem buffers are sent before the FAX Modem disconnects. If S38 is set between 0 and 254, the FAX Modem will wait that number of seconds for the remote FAX Modem to acknowledge all data in the FAX Modem buffer before disconnecting. If time expires before all data is sent, the NO CARRIER result code will be issued to indicate that data has been lost. If all data is transmitted prior to timeout, the response to the ATHO command will be OK. If S38 is set to 255, the FAX Modem does not timeout, and continues to attempt to deliver data in the buffer until the connection is lost, or the data is delivered. S39 Reserved S40 BIT MAPPED OPTIONS (MNP) Indicates the status of command options. Range: None Default: 55 (i.e. 00110111) Bit 0,1 = AT/N Bit 2,3,4 = AT/K Bit 5,6 = AT/A Bit 7 = AT/G S41 BIT MAPPED OPTIONS (MNP) Indicates the status of command options. Default: 1 (i.e. 00000001) Bit 0 = AT%C Bit 1 = AT%E Bit 2 = AT\L Bit 3,4,5,6,7 = Not used. S46 PROTOCOL SELECTION Controls selection of compression The following actions are executed for the given values: S46 = 136 Execute error correction protocol with no compression. S46 = 138 Execute error correction protocol with no compression. In addition to V.42 bis, the FAX Modem also implements MNP5 data compression. V.42 bis is used only with LAPM, and MNP5 only with MNP4. S48 V.42 NEGOTIATION ACTION The V.42 negotiation process determines the capabilities of the remote FAX Modem. However, when the capabilities of the remote FAX Modem are known and negotiation is unnecessary, this process can be bypassed if desired. Range: 0,7 or 128. If an invalid number is entered, it is accepted into the S register, but S-48 will act as if 128 entered. S48 = 0 Disable negotiation; bypass the detection and negotiation phases; and proceed with LAPM. S48 = 7 Enable negotiation. S48 = 128 Disable negotiation; bypass the detection and negotiation phase; and proceed at once with the fallback action specified in S36. Can be used to force MNP. S49 SPEED BUFFER LOWER LIMIT This S-register, in conjunction, with S50, determines the number of characters which are buffered in the terminal buffer in Speed Buffering Mode before the DTE is flow controlled. When the number of characters in the buffer reach the value set by this register, the DTE is flowed on. If S49 and S50 are set to invalid values (e.g., if low limit value > high limit value, or S49>S49), the values will be automatically readjusted to match those of the FAX Modem buffer. Range: 1 to 249 Default: 8 S50 SPEED BUFFER UPPER LIMIT This S-register, in conjunction with S49, determines the number of characters which are buffered in the terminal buffer in Speed Buffering mode before the DTE is flow controlled. When the number of characters in the buffer reach the value set by this register, the DTE is flowed on. If S49 and S50 are set to invalid values (e.g., if low limit value>high limit value, or S50 is not between 2 and 250), the values will be automatically readjusted to match those of the FAX Modem buffer. Range: 2 to 250. Default: 255 (Intentionally set to an invalid value). S82 BREAK HANDING OPTIONS Break signals provide a way for the user to get the attention of the remote FAX Modem. The break type depends on the specific application. LAPM specifies three methods of break signal handing: in sequence, expedited, destructive Range; 3,7, or 128. If an invalid number is entered, it is accepted into the S register, but S82 will act as if 128 entered. S82 = 3 Expedited: FAX Modem sends a break immediately; data integrity is maintained both ahead of and after the break. S82 = 7 Destructive: FAX Modem sends a break immediately; data being processed by each FAX Modem at the time of the break is destroyed. S82 = 128 In Sequence: FAX Modem sends a break in sequence with any transmitted data; data integrity is maintained both ahead of and after the break. S86 CONNECTION FAILURE CAUSE CODE When the FAX Modem issues a NO CARRIER result code, a value is written to their S register to help determine the reason for the failed connection. S86 records the first event that contributes to a NO CARRIER message. The cause codes are: S86 = 0 Normal disconnect, no error occurred. S86 = 4 Loss of carrier. S86 = 5 V.42 negotiation failed to detect an error-correction FAX Modem at the other end. S86 = 9 The FAX Modem could not find a common protocol. S86 = 12 Normal disconnect initiated by the remote FAX Modem. S86 = 13 Remote FAX Modem does not respond after 10 re-transmissions of the same message. S86 = 14 Protocol violation,. S91 PROGRAMMABLE TRANSMIT LEVELS The transmit level is adjustable in S91 from 0 dBm (U.S. Default value) to -15 dbm (Japan Default value) in 1 dB increments for data transmission in both synchronous and asynchronous operation. This Register takes effect when the Japanese parameters are enabled or a leased line is selected. S91 = 0 0dBm S91 = 1 -1dBm S91 = 2 12dBm . . . S91 = 14 -14dBm S91 = 15 -15 dBm (default value for Japan) The transmit level may not be changed once a connection exists. S95 EXTENDED RESULT CODES The bits in this register can be set to override some of the ATWn command options. A bit set to a 1 in this register will enable the corresponding result code regardless of the ATWn setting. Bit 0 = Connect result code indicates DCE speed instead of DTE speed. Bit 1 = Append / ARQ to verbose CONNECT XXXX result code if protocol is not NONE. Bit 2 = Enable CARRIER XXXX result code. Bit 3 = Enable PROTOCOL XXX result code. Bit 4 = Reserved. Bit 5 = Enable COMPRESSION result code. Bit 6 = Reserved. Bit 7 = Reserved. (SMC/all-07/05/94)