2400-BPS (250-3025B) Internal Modem Registers Faxback Doc. # 5793 Your modem has 19 registers. These registers are memory locations inside your modem. These registers control some aspects of your modem's operation. You usually do not have to worry about setting any register. The default values work for most applications. REGISTER SUMMARY The following chart summarizes your modem's registers. ┌────────┬─────┬──────────┬───────┬─────────────────────────┐ │REGISTER│RANGE│ UNIT │DEFAULT│DESCRIPTION │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ SO │0-255│ rings │ 0 │Ring to answer on │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S1 │0-255│ rings │ 0 │Number of rings passed │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S2 │0-127│ ASCII │ 43 │Escape code character │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S3 │0-127│ ASCII │ 13 │Command terminator │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S4 │0-127│ ASCII │ 10 │Line feed character │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S5 │0-127│ ASCII │ 8 │Backspace character │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S6 │0-255│ seconds │ 2 │Wait time for dial tone │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S7 │0-255│ seconds │ 30 │Wait time for carrier │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S8 │0-255│ seconds │ 2 │Pause time for comma │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S9 │0-255│ 1/10 sec │ 6 │Carrier detect response │ │ │ │ │ │time │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S10 │0-255│ 1/10 sec │ 14 │Carrier loss hangup delay│ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S11 │0-255│1/100 sec │ 95 │Touch-tone timing │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S12 │0-255│ 1/50 sec │ 50 │Escape code timing │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S13 │ │ Not used │ │ │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S14 │ │Bit mapped│ │Option register │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S15 │ │ Not used │ │ │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S16 │ │Bit mapped│ │Option register │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S17 │ │ Not used │ │ │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S18 │0-255│ seconds │ 0 │Test duration │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S19 │ │ Not used │ │ │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S20 │ │ Not used │ │ │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S21 │ │Bit mapped│ │Option register │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S22 │ │Bit mapped│ │Option register │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S23 │ │Bit mapped│ │Option register │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S24 │ │ Not used │ │ │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S25 │0-255│ seconds │ 5 │Delay to DTR │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S26 │0-255│ seconds │ │RTS - CTS delay interval │ ├────────┼─────┼──────────┼───────┼─────────────────────────┤ │ S27 │ │Bit mapped│ │Option register │ └────────┴─────┴──────────┴───────┴─────────────────────────┘ VIEWING REGISTER To view the contents of a register, in the command mode type: ATSr? ENTER Where r is the register number. Your modem returns: nn Where nn is the current setting of the register. OK You can view the contents of several registers with one command: ATSr?Sr?Sr? ENTER Your modem returns: nn First register nn Second register nn Third register OK SETTING REGISTERS To change the contents of a register, in the command mode type: ATSr=n ENTER Where r is the register number and n is the new value. Your modem returns: OK You can set the contents of several registers with one command: AT Sr=n Sr=n Sr=n ENTER Your modem returns: OK REGISTER S0-AUTO ANSWER CONTROL This register determines how many times your phone rings before your modem answers. If you set this register to 0, your modem does not answer the telephone. The default value for this register is 0. REGISTER S1-RING COUNTER This register contains the count of the current number of rings. If your telephone does not ring again within 8 seconds, the register resets to 0. You should never need to set the value in this register. REGISTER S2-ESCAPE CODE ASCII VALUE This register contains the ASCII value of the escape code. You must set this value to a legitimate ASCII character within the range 0-127. Setting this code to greater than 127 disables the escape code. See "Switching From the Communications to the Command Mode" in "Dialing and Answering with the AT Command Set," earlier in this manual. The default value for this register is 43 (ASCII value of +). REGISTER S3-COMMAND TERMINATOR This register contains the ASCII value of the character you use to end and execute a command. You should never need to change this value. The default for this register is 13 (ASCII value of ENTER). REGISTER S4-LINE FEED ASCII VALUE This register sets the character your modem sends after any result code. Your should never need to change this value. If you do not want your modem to send a line feed after the result code, set this register to 0. The default value for this register is 10 (ASCII value for line feed). REGISTER S5-BACKSPACE ASCII VALUE This resets the character your modem uses as a backspace character for editing. You do not normally need to change this register. The default value is 8 (ASCII backspace). REGISTER 6-WAIT FOR DIAL TONE DURATION This register sets how many seconds your modem waits to begin dialing after it goes off hook. If your modem begins dialing before the dial tone starts, your call might not go through. You can set this register to a higher value to provide a longer delay. The default value is 2 (setting to 0 or 1 also give a 2 second delay). REGISTER S7-WAIT FOR CARRIER DURATION This register sets how long your modem waits after dialing to detect a carrier from an answering modem. If this time expires without a carrier detect, your modem returns the NO CARRIER result code. The default value is 30. REGISTER S8-DIALING PAUSE (,) DURATION This register sets how many seconds your modem pauses when it encounters a comma (,) in the dialing sequence. If you dial from a system that requires a second dial tone (like a PABX system), you might need to increase the duration of this pause if your modem is not waiting long enough for an outside line. The default value is 2. REGISTER S9-CARRIER DETECT RESPONSE TIME Sets the length of time for the modem to acknowledge a valid carrier. Default is 6/10 seconds. REGISTER S10-CARRIER LOSS TO DISCONNECT DURATION This register sets how many tenths of a second (1/10 seconds) your modem waits to disconnect from the phone line after the other modem's carrier stops. In some areas with poor quality phone service, the carrier can occasionally drop out and cause your modem to disconnect during a call. If you set this register to 255, your modem considers the carrier always present. The default value is 14 (1.4 seconds). REGISTER S11-TOUCH TONE DIALING SPEED This register controls the dialing rate during tone dialing (no effect on pulse dialing). The default value of 95 sets a rate of about seven digits per second. REGISTER S12-ESCAPE CODE GUARD TIME This register sets the length of time (in 1/50 second increments) you must pause before and after the escape code for your modem to recognize the escape code. See "Switching From the Communications to the Command Mode" in "Dialing and Answering the AT Command Set," earlier in this manual. The default value is 50 (1 second). REGISTER S13-NOT USED REGISTER S14-BIT MAPPED OPTIONS This register is a bit-mapped register that shows the status of some of the operation options. Normally, you do not write to this register. You use specific commands to set these options. BIT VALUE DESCRIPTION 0 Not used 1 0 Local echo disabled 1 Local echo enabled 2 0 Result codes enabled 1 Result codes disabled 3 0 Result codes as numbers Result codes as words 4 Not used 5 0 Tone dial 1 Pulse dial 6 Not used 7 0 Answer mode Originate mode REGISTER S15-NOT USED REGISTER S16-TEST MODE OPTION REGISTER This register is a bit-mapped register that shows the status of the test functions. Normally you don't write to this register. You use the &T command to change these options. See "Modem Test Commands" for more information. BIT VALUE DESCRIPTION 0 0 Analog loopback disabled 1 Analog loopback enabled (&T1) 1 Not used 2 0 Digital loopback disabled 1 Digital loopback enabled (&T3) 3 0 Loopback not in process 1 Responding to remote digital loopback 4 0 Remote digital loopback disabled 1 Remote digital loopback enabled (&T6) 5 0 Remote digital loopback, self test disabled 1 Remote digital loopback, self test enabled (&T7) 6 0 Analog loopback with self test disabled 1 Analog loopback with self test enabled (&T8) 7 Not used REGISTER S17-NOT USED REGISTER S18-TEST TIMER This register controls the duration in seconds for the test. The default value is 0. This causes the modem to perform any test until you cancel it with the &T0 command. See "Modem Test Commands" for more information. REGISTER S19-NOT USED REGISTER S20-NOT USED REGISTER S21-BIT MAPPED OPTIONS This register is a bit-mapped register that shows the status of the &D, &C, and Y commands. You do not normally write to this register. Use the individual commands to affect these options. BIT VALUE DESCRIPTION 0 Not used 1 Not used 2 Not used 3,4 00 &D0 (Forced DTR) 10 &D1 (Async command state) 01 &D2 (On hook, async command state, disabled auto answer) 11 &D3 (Assumes initialization state) 5 0 &C0 (Carrier detect forced) 1 &C1 (Carrier detect true) 6 Not used 7 0 Y0 (Disable long space disconnect) 1 &Y1 (Enable long space disconnect) REGISTER S22-BIT MAPPED OPTIONS This register is a bit-mapped register that shows the status of the M, X, and &P commands. You do not normally write to this register. Use the individual commands to affect these options. BIT VALUE DESCRIPTION 0,1 Not used 2,3 00 M0 (Speaker disabled) 10 M1 (Speaker disabled during data transfer) 01 M2 (Speaker always on) 11 M3 (Speaker disabled during dialing & data transfer) 4,5,6 000 X0 (Result code status) 100 X1 (Result code status) 101 X2 (Result code status) 110 X3 (Result code status) 111 X4 (Result code status) 7 0 &P0 (U.S. make/break dial pulse ratio) 1 &P1 (U.K./Hong Kong make/break dial pulse ratio) REGISTER S23-BIT MAPPED OPTIONS This register is a bit-mapped register that shows your modem's current communications settings, and the status of the &G command. You do not normally write to this register. The modem sets the communications settings automatically. BIT VALUE DESCRIPTION 0 0 Response to remote digital loopback disabled. Response to remote digital loopback enabled. 1,2 00 300 bps 10 12 bps 11 24 bps 3 Not used 4,5 00 Even parity 10 Space parity 01 Odd parity 11 Mark/No parity 6,7 00 &G0 (No guard tone) 10 &G1 (550 Hz guard tone) 01 &G2 (1800 Hz guard tone) REGISTER S24-NOT USED REGISTER S25-DELAY TO DTR This register determines the delay to DTR. The interpretation of the value stored in S25 depends on the &Q mode. A change in the state of DTR from ON to OFF will be ignored if it is less than the value specified in S25 (in 0.01 seconds increments). REGISTER S26-RTS TO CTS DELAY INTERVAL This register specifies the delay after an OFF-to-ON transition of Request-to-Send before Clear-to-Send is asserted when the &R0 option is in effect (default). The range of values will be from 0 to 2.55 seconds with a 10 millisecond resolution. The S26 values are 0-255 (255 x 10 mS = 2.55 seconds). The default for this register is 1. REGISTER S27-BIT MAPPED OPTIONS This register is a bit-mapped register that shows the status of the B command. You do not normally write to this register. Use the B command to affect the status of this register. BIT VALUE DESCRIPTION 0-5 Not used 6 0 B0 CCITT V.22bis/V.22 1 B1 Bell 212A 7 Not used (SMC/BKL-02/28/96)