S-Registers

Understanding Bit-Mapped S-Registers

A bit-mapped S-Register uses one number to describe a collection of settings. Bit-mapping allows us to pack a lot of information in a small space.

Bit-mapped registers are in the form of Sr.b=n, where r is the bit-mapped register;.b is the bit; n is 0 (off) or 1 (on).

The modem displays the value of an S-Register, as a decimal value between 0 and 255. The modem, however, understands the decimal value as a collection of binary digits (bits).

How bits are mapped to decimal values

Bits can be mapped into decimal values. Each bit can be either on (1) or off (0). Eight bits create 256 unique combinations of 1s and 0s. Each of the eight bits can be assigned a number corresponding to its position:

b b b b b b b b
7 6 5 4 3 2 1 0

Also, each bit can be assigned a value corresponding to its number (e.g., the value equals 2 to the power of the bit):

Bit Value
7
128
6
64
5
32
4
16
3
8
2
4
1
2
0
1

Converting Bits to Decimal Values

Starting with a string of eight bits, assign each "1" bit a value based on its position. Add the values to come up with the final decimal value.

Here’s an example of how bits are converted to decimal values:

01001111

0 1 0 0 1 1 1 1
0 + 64 + 0 + 0 + 8 + 4 + 2 + 1 = 79

Converting Decimal Values to Bits

Convert decimal values to bits by finding the largest decimal equivalent that is less than the decimal value. Subtract the decimal equivalent and mark the equivalent bit "1." Continue until the decimal value is zero. See the example below.

113
113 - 64 = 49
01
49 -32 = 17
011
17 -16 = 1
0111
1 -1 = 0
01110001

Setting Bit-Mapped S-Registers

You can set bit-mapped S-Registers using either bits or decimal values. While it may be simpler for you to set the bits individually, your modem displays the S-Register settings in decimal form.

Using Bits

Turning individual bits on and off is the more direct way to set bit-mapped S-Registers. To do this, specify the S-Register that you want to set and then indicate which bits you want to turn on (1) or off (0).

Example: ATS13.0=1.4=1.5=1, turns bits 0, 4, and 5 on for S-Register 13.

Using Decimal Values

An alternative way to set bit-mapped S-Registers is by adding the decimal values of the bits and entering the total.

This example, ATS13=49, sets the same value as the one in Using Bits above.

A complete list of S-Registers

Register Default Function
S0 0 Sets the number of rings on which to answer in Auto Answer mode. S0=0 disables Auto Answer. S0=1 enables Auto Answer and the Courier 56K Business Modem answers on the first ring.
S1 0 Counts and stores the number of rings from an incoming call.
S2 43 Stores the ASCII decimal code for the escape code character. Default character is “+”. A value of 128-255 disables the escape code.
S3 13 Stores the ASCII decimal code for the Carriage Return character. Valid range is 0-127.
S4 10 Stores the ASCII decimal code for the Line Feed character. Valid range is 0-127.
S5 8 Stores the ASCII decimal code for the Backspace character. A value of 128-255 disables the Backspace key's delete function.
S6 0 Set the number of seconds the Courier 56K Business Modem waits for a dial tone.
S7 60 Sets the number of seconds the Courier 56K Business Modem waits for a carrier. May be set for much longer duration if, for example, the Courier 56K Business Modem is originating an international connection.
S8 2 Sets the duration, in seconds, for the pause (,) option in the Dial command and the pause between command reexecutions (> and A> commands).
S9 6 Sets the required duration, in tenths of a second, of the remote device's carrier signal before recognition by the Courier 56K Business Modem.
S10 14 Sets the duration, in tenths of a second, that the Courier 56K Business Modem waits after loss of carrier before hanging up. This guard time allows the Courier 56K Business Modem to distinguish between a line hit, or other disturbance that momentarily breaks the connection, and a true disconnect (hanging up) by the remote device.
S11 70 Sets the duration and spacing, in milliseconds, of dialed tones.
S12 50 Sets the duration, in fiftieths of a second, of the guard time for the escape code (+++) sequence.
S13 0 Bit-mapped register. See the beginning of this section for information about setting bit-mapped registers.
Bit Value Result
0 1 Reset when DTR drops.
1 2 Reverse normal Auto Answer operation: On incoming RING, enter Originate Mode and look for an answer tone.
2 4 Disable 250 ms pause before result code display.
3 8 On DTR signal, autodial the number stored in NVRAM at position 0.
4 16 At power-on/reset, autodial number stored in NVRAM at position 0.
5 32 Disable HST (used for testing V.32terbo in Dual Standard Courier 56K Business Modems).
6 64 Disable MNP Level 3 (used for testing Level 2).
7 128 Hardware reset (works like powering off and then on).
S14 0 Bit-mapped register ( See the beginning of this section for information about setting bit-mapped registers).
Bit Value Result
0 1 Disconnect on escape code.
S15 0 Bit-mapped register. ( See the beginning of this section for information about setting bit-mapped registers).
Bit Value Result
0 1 Disable the Courier 56K Business Modem's extra high-frequency equalisation if it causes problems on shorter-link calls for HST modulation only.
1 2 Disable online fallback.
2 4 Disable 450 bps back channel HST only.
3 8

Reset non-ARQ mode Transmit buffer from 1.5K bytes to 128.

The default 1.5K byte non-ARQ buffer allows data transfer with X- and Y-modem type File Transfer Protocols without using flow control.
The 128-byte option allows remote users with slower modems to stop your transmitted data from scrolling off their screens. When remote users send your computer an XOFF (<Ctrl-S>) and you stop transmitting, the data in transit doesn’t exceed the size of their screen.

4 16 Disable MNP Level 4; retransmitting the larger Level 4 data blocks may be a problem if you expect a great number of errors during a call.
5 32 Set Backspace key to delete.
6 64 Some earlier 2400 bps MNP modems, not made by U.S. Robotics or Microcom, were not fully compatible with the MNP protocol. If you have difficulty making a successful 2400 bps MNP connection with a remote MNP modem, it may be because of this incompatibility. Set S15 to 64 and try again to make the connection.
7 128 Custom applications only.
S16 0 Bit-mapped register. ( See the beginning of this section for information about setting bit-mapped registers). For testing, refer to the Testing the Connection section of the Contents section.
Bit Value Result
1 2 Dial Test.
2 4 Test pattern.
3 8 Remote digital loopback.
S18 0 Test timer for software-initiated loopback testing (&Tn); disabled when S18 is set to 0. Used to set the duration of testing, in seconds, before the Courier 56K Business Modem automatically times out and terminates the test.
S19 0 Sets the duration, in minutes, for the Inactivity Timer. The timer activates when there is no data activity on the R232 interface, and at the timeout the Courier 56K Business Modem hangs up. S19=0 disables the timer.
S21 10 Sets, in 10-millisecond units, the length of breaks sent from the Courier 56K Business Modem to the computer or terminal. Applies to ARQ mode only.
S22 17 Stores the ASCII code for the XON character.
S23 19 Stores the ASCII code for the XOFF character.
S24 150 Sets the duration, in 20-millisecond units, between pulsed DSR signals when the Courier 56K Business Modem is set to &S2 or &S3. The default is 3 seconds.
S25 5 Sets DTR recognition time in 10-millisecond units.
S26 1 Sets duration, in 10-millisecond units, of the delay between RTS and the CTS in synchronous mode.
S27 0 Bit-mapped register. ( See the beginning of this section for information about setting bit-mapped registers).
Bit Value Result
0 1 Enable ITU-T V.21 modulation at 300 bps for overseas calls. In V.21 mode, the Courier 56K Business Modem answers both Bell 103 and V.21 calls, but only originates V.21 calls.
1 2 Enable unencoded (non- trelliscoded) modulation in V.32 mode; this option is part of the ITU-T V.32 recommendation, but is rarely used.
2 4 Disable V.32 modulation; used for testing HST modulation.
3 8 Disable 2100 Hz answer tone to allow two V.42 devices to connect more quickly.
4 16 See error control handshaking options below.
5 32 See error control handshaking options below.
6 64 Disable V.42 Detect Phase
7 128 Unusual software incompatibility. Some software may not accept some result codes. This setting disables the codes and displays the 9600 code instead. The call's actual rate can be viewed on the ATI6 screen.
Error control handshaking options: Select the total value of bits 4 and 5
Bit 4 Bit 5 Result
0 0 Complete handshaking sequence: V.42 Detection, LAPM error control, MNP.
16 0 Disable MNP.
0 32 Disable V.42 Detection and LAPM.
16 32 Disable Detection phase, if you know that the remote Courier 56K Business Modem does LAPM, but not the Detection phase.
S28 8 Sets the duration in tenths of a second of the extra 3000/600 Hz answer tones sent during V.32 hand-shaking. This gives V.32 modems additional time to connect in V.32 mode before timing out.
If there is difficulty answering older, manually operated V.32 modems (for example, modems that require a button to be pushed in order to dial), try lengthening the duration of the extra tones. Setting S28 to zero eliminates the extra tones resulting in a faster connect time if, for example, the Courier 56K Business Modem is set to use V.21 modulation (300 bps) or V.23 modulation (1200 bps).
S29 20 Sets the duration, in tenths of a second, of the V.21 answer tone.
S32 9 Assign Voice/Data switch function
Value Function
0 Disabled
1 Voice/Data- originate mode
2 Voice/Data- answer mode
3 Redial last number
4 Dial number stored at position 0
5 Auto answer on/off toggle
6 Reset modem
7 Initiate remote digital loopback
8 Busy out the phone line toggle
9 Execute stored command (see &ZC command)
S34 0 Bit-mapped register. See the beginning of this section for information about setting bit-mapped registers.
Bit Value Result
0 1 Disable V.32 bis. Used for troubleshooting; Technical Support may ask you to disable V.32bis for testing purposes.
1 2 Disable the Courier 56K Business Modem's enhanced, proprietary V.32bis modulation. Used for troubleshooting.
2 4 Disable the faster retrains that occur during proprietary V.32 terbo modulation. Used for troubleshooting.
3 8 Enable V.23. Required for some British connections.
4 16 Change MR LED to DSR
6 64 Disable the remote-access busy message.
7 128 Disable V.32 terbo.
S38 0

Sets the duration, in seconds, before a forced hang-up and clearing of the Transmit buffer when DTR drops during an ARQ call.

This is provided to allow time for a remote device to acknowledge receipt of all transmitted data. Default = 0: The Courier 56K Business Modem immediately hangs up when DTR drops. If the Courier 56K Business Modem receives the ATH command, it ignores S38 and immediately hangs up.

S41 0

Sets the number of allowable remote-access login Attempts, thus enabling or disabling remote access.

The default setting of zero allows no remote login Attempts, disabling remote access. A value of 1 or greater enables remote access. If the number of unsuccessful login Attempts exceeds the limit set by this register, the Courier 56K Business Modem returns online and any further login Attempts during the remainder of that connection are refused.

S42 126 Stores the ASCII decimal code for the remote-access escape character. The default character is a tilde (~).
S43 200 Sets the duration, in fiftieths of a second, of the guard time for the remote-access (~~~~) sequence.
S44 15 Sets the duration, in seconds, of the interval between losing carrier and reestablishing a connection.
S51 0 Bit-mapped register. See the beginning of this section for information about setting bit-mapped registers.
Bit Value Result
0 1 Disable MNP/V.42 for V.22 (1200 bps)
1 2 Disable MNP/V.42 for V.22 bis (2400 bps)
2 4 Disable MNP/V.42 for V.32/V.32 bis/V.32 terbo (9600/14400/19200/21600 bps).
6 64 Disable Selective Reject
S53 126 Bit-mapped register. ( See the beginning of this section for information about setting bit-mapped registers).
Bit Value Result
0 1 Dial security enabled.
1 2 Prompting enabled.
2 4 Local-access password protection enabled.
3 8 DTMF security enabled.
Enabling local-access password protection disables the &Zn=s command (which stores up to 10 phone numbers) because stored phone numbers occupy the same space in NVRAM as the dialback numbers for Dial Security accounts.
S54 64 Symbol rate bit-mapped register used primarily by Technical Support for debugging purposes.
Bit Value Result
0 1 Disable 2400 symbol rate.
1 2 Disable 2743 symbol rate.
2 4 Disable 2800 symbol rate.
3 8 Disable 3000 symbol rate.
4 16 Disable 3200 symbol rate.
5 32 Disable 3429 symbol rate.
6 64 Disable Call Indicate (CI).
7 128 Disable V.8.
S55 0 Trellis code bit-mapped register used primarily by U.S. Robotics Technical Support for debugging purposes.
Bit Value Result
0 1 Disable 8S-2D mapping.
1 2 Disable 16S-4D mapping.
2 4 Disable 32S-2D mapping.
3 8 Disable 64S-4D mapping.
7 128 Enable phase roll detection
S56 0 Bit-mapped register primarily used by Technical Support for debugging purposes.
Bit Value Result
0 1 Disable non-linear coding.
1 2 Disable TX level deviation.
2 4 Disable preemphasis.
3 8 Disable precoding.
4 16 Disable shaping.
5 32 Disable V.34+
6 64 Disable V.34.
7 128 Disable V.FC.
S58 0 Bit-mapped register. (See the beginning of this section for information about setting bit-mapped registers.)
Bit Value Result
1 2 Disable Bler Monitor
5 32 Enables/Disables V.90
6 64 Disables V.92 functions
S59 0 Bit-mapped register. (See the beginning of this section for information about setting bit-mapped registers).
Bit Value Result
0 1 Disable enhanced V.42bis
1 2 Alternate Caller ID timing
S69 0 Bit-mapped register. (See the beginning of this section for information about setting bit-mapped registers).
Bit Value Result
0 1 Disable external Plug and Play
1 2 Enable Auto Redial
2 4 See HS LED options below
3 8 See HS LED options below
5 32 Disable Digital Line Guard
6 64 Disable Loop Monitor
HS LED options: Select the total value of bits 2 and 3
  Bit 2 Bit 3 Result
  0 0 HS LED is on at 2400 and above
  4 0 HS LED is on at 14400 and above
  0 8 HS LED is on at 16800 and above
  4 8 HS LED is on at V.90/V.92 and above
S70 0 Bit-mapped Register. (See the beginning of this section for information about setting bit-mapped registers.)
Bit Value Result
0 1 Enable recognition of Ring A
1 2 Enable recognition of Ring B
2 4 Enable recognition of Ring C
3 8 Enable recognition of Ring D
4 16 Enable recognition of Ring E
S71 0 RCID request delay (1/200 sec)
S72 0 Bit-mapped Register. (See the beginning of this section for information about setting bit-mapped registers.)
Bit Value Result
0 1 # of requests
1 2 # of requests
2 4 # of requests
3 8 Request duration * 10 mS
4 16 Request duration * 10 mS
5 32 Request duration * 10 mS
6 64 Request duration * 10 mS
7 128 Request duration * 10 mS
S73 0 Bit-mapped Register. (See the beginning of this section for information about setting bit-mapped registers.)
Bit Value Result
0 1 Request level
1 2 Request level
2 4 Request level
3 8 Request pause * 10 mS
4 16 Request pause * 10 mS
5 32 Request pause * 10 mS
6 64 Request pause * 10 mS
7 128 Request pause * 10 mS