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Cermetek Microelectronics, Inc. 

High Speed Modem and FAX Family 

 

2003 Cermetek Microelectronics, Inc. 

Page 9 

Document No. 607-0003 Revision K3 (09/03) 

AT COMMAND APPLICATIONS 

Dialing a Phone Number.

  The Dial command takes 

the form 

Dn

, where n is a string of characters.  In the 

simplest form, n will be only the digits of the phone 
number to be dialed. 
 
Example: Dial 

Number. 

Enter: 

ATD1234567<CR>

 

 
In response to this command, the HS Modem dials the 
telephone number “123-4567” and then waits for a 
carrier from the distant modem.  If no carrier is 
detected within a given time (the default time is 30 
seconds), the HS Modem automatically releases the 
line and sends a NO CARRIER result code.  If a 
carrier is detected, the HS Modem gives a CONNECT 
result code and goes on-line, permitting 
communication with the distant modem. 
 
The Dial command may also be issued without a 
telephone number.  ATD causes the modem to pick up 
the telephone a line without dialing a number. 
 

Pause During Dialing.

  When placing a call from an 

office with a telephone connected to a PBX, it may be 
necessary to dial an access code (usually the digit 9) 
to get an outside line.  Inserting a comma in the 
telephone number commands the modem to pause for 
a specific length of time.  The factory default pause 
time is 2 seconds. 
 
Example:  Dial 9, pause, dial number. 
Enter: 

ATDT9, T1234567<CR>

 

Result: 

OK<CR><LF>

 

 
Multiple commas may be used for a greater delay 
time. 
 

Touch Tone and Pulse Dialing.

  The modem can use 

DTMF (touch-tones) 

T

, or dial pulses 

P

 when dialing a 

telephone number.  If the dial command does not 
specify which type to use, the modem defaults to the 
type last specified.  The power-on default value is 

T

 
Example:  Pulse dial 9, pause, touch-tone dial 

number. 

Enter: 

ATDP9, T1234567<CR>

 

Result: 

OK<CR><LF>

 

 

Redial Last Number.

    Use 

A/

, the repeat command, 

to redial the last telephone number dialed when a busy 
signal is received. 
 

Go Off-Hook and Return to Command State.

    The 

modem can be forced to reenter the command state 
after going off-hook by issuing the ATDT command 
with a semi-colon.  This is useful when using the 
modem with an independent DTMF tone generator. 
 

Example:  Touch-tone dial 9, pause, go off-hook, 

return for additional 

AT

 commands. 

Enter: 

ATDT9, T;<CR>

 

Result: 

OK<CR><LF>

 

 

Automatic Answering. 

S0=0* 

DO NOT ANSWER TELEPHONE 

S0=1-254  ANSWER ON RING 1 TO RING 254 
S0=255 

ANSWER ON RING 255 

 
*When S0 is set to 0, the modem will not auto-answer. 
 
 

PHONE LINE CONNECTION GUIDELINES 

1.  The HS Modem must be mounted in the final 

assembly such that it is isolated from exposure to 
any hazardous voltages within the assembly.  
Adequate separation and restraint of cables and 
cords must be provided. 

 
2.  The circuitry from the HS Modem to the 

telephone line interface must be provided in 
wiring that carries no other circuitry other than 
that specifically allowed in the FCC rules (such as 
A and A1 leads). 

 
3.  Connection to phone line should be made 

through an RJ-11C jack. 

 
4. 

PCB traces from the modem’s RING and TIP pins 
to the RJ-11C jack must be 0.1 inch spacing or 
greater to one another and 0.2 inch spacing or 
greater to all other traces.  The traces should 
have a nominal width of 0.020 inches or greater. 

 
5.  The RING and TIP PCB traces should be as 

short as possible and oriented to prevent 
coupling other high speed or high frequency 
signals present on the host circuit PCB. 

 
6.  No additional circuitry other than that shown in 

Figure 7 may be connected between the modem 
module and the RJ-11C jack.  Doing so will 
invalidate the FCC approval. 

 
7.  The HS Modem, the RJ-11C jack, the interfacing 

circuitry and all PCB traces in between, must be 
contained on a PCB with a 94 V-0 flammability 
rating. 

 
8.  The supplied FCC registration label must be 

applied visibly on the outside of the product. 

 
9.  The product’s User Manual must provide the user 

with instructions for connection and use as 
recommended in the FCC Registration Section 
below. 

Содержание CH1794

Страница 1: ...mum DTE rate of 57 6kbps for the CH1794 115 2kbps for the CH1799 and 230 4kbps for the CH2056 A choice of error correcting schemes is available including MNP 10 for cellular telephone applications The HS Modem family supports Send and Receive FAX The CH1799LL operates exclusively on non voltage bearing leased The HS Modem family is pin compatible with Cermetek s low cost CH1786 V 22bis 2400bps mod...

Страница 2: ...amily of products satisfies U S and Canadian requirements and will meet other international approval agency requirements that specify these levels of isolation The TBR ETBR variants also meet the European TBR21 requirements Pins 1 and 2 function as both input and output connections to the PSTN To maximize field reliability in hostile environments for Canadian approval for UL compliance and also op...

Страница 3: ...iods the power may be switched off using external circuitry and then reapplied when the HS Modem s RI pin becomes active The HS Modem can thus be powered down to zero Referring to Figure 2 the controller activates the relay switch supplying power 5V to the HS Modem In this configuration the ring signal is used to wake up the HS Modem when the HS Modem is in the power down state The internal struct...

Страница 4: ...auses an overall throughput data rate penalty Voice Tone Injection Port The HS Modem Family provides pin T1 to allow the user to share the PSTN line interface associated with the modem for voice and DTMF applications Figure 5 contains a schematic which uses a 5 Volt single supply operational amplifier and indicates one possible configuration for voice tone utilization Refer to Cermetek Application...

Страница 5: ...ed by 3 escape characters followed by a second guard time At power up the guard time is set to 1 second and the escape character is set as Note that a 50 msec delay is required between escape characters These two parameters can be modified via registers S2 and S12 respectively The HS modem will stay off hook with its carrier on after the escape sequence is received The HS Modem will return an OK s...

Страница 6: ...TE speed and parity odd even mark space or none These activities are briefly described below HS Modem Reset Upon applying power to the HS Modem the HS Modem automatically generates an internal reset pulse The user can also reset the modem externally by applying a high going reset pulse to the RST pin for at least 10 msec after the 5V power supply has stabilized Delay sending commands to the HS Mod...

Страница 7: ...1799LL is a leased line version of the CH1799 Whereas the CH1799 requires an active voltage bearing or wet PSTN line for normal operations typically 48VDC on hook line voltage the CH1799LL is designed to operate over a non voltage bearing or dry line The CH1799LL will only operate properly on a dry line Damage will occur if used on a wet line The CH1799LL does not support ring detect but does supp...

Страница 8: ...odem DTR should be set LOW when not used 14 DSR O DATA SET READY LOW indicates handshaking with a remote modem is in progress and or the data carrier of a remote modem has been detected 15 RI O RING INDICATION This signal follows the frequency of the ringing signal and is normally about 20 to 40 Hz for 2 seconds on with 4 seconds off 16 CTS O CLEAR TO SEND Active LOW Indicates that the modem is re...

Страница 9: ...f Hook and Return to Command State The modem can be forced to reenter the command state after going off hook by issuing the ATDT command with a semi colon This is useful when using the modem with an independent DTMF tone generator Example Touch tone dial 9 pause go off hook return for additional AT commands Enter ATDT9 T CR Result OK CR LF Automatic Answering S0 0 DO NOT ANSWER TELEPHONE S0 1 254 ...

Страница 10: ...ke all repairs to all products in the HS Modem family If repairs are necessary after installation of the HS Modem and the end product has been delivered to the end user the end product must be returned to the end product supplier where the HS Modem can be removed and then forwarded to Cermetek for repair The following notice is recommended and should be included in the end product s user manual FO...

Страница 11: ...ion Long space disconnect disabled Speaker enabled but off when receiving carrier Speaker volume set to low Local modem will not grant RDL request from remote modem Guard tones disabled Minimum DTR pulse width 05 seconds Ring count 00 Escape code character 43 Flash to on hook 70 msec Auto speed detection enabled DTE connect speed connect messages Back space character 08 BS Carriage return characte...

Страница 12: ... X X X X X 56 CARRIER 24000 X X X X X 57 CARRIER 26400 X X X X X 58 CARRIER 28800 X X X X X Table 5B CH1799 Extended Result Codes Continuation Result Code Form n is ATXn Command Terse or Short Verbose or Long 0 1 2 3 4 59 CARRIER 16800 1 X X X X 61 CARRIER 21600 1 X X X X 62 CARRIER 24000 1 X X X X 63 CARRIER 26400 1 X X X X 64 CARRIER 28800 1 X X X X 66 Compression Class 5 X X X X X 67 Compressio...

Страница 13: ...Directory n 0 to 3 E0 Turn off command echo E1 Turn on command echo Table 6A Summary of Basic AT Commands Continuation Command Function H0 Initiate a hang up sequence H1 If on hook go off hook and enter command mode L0 Set low speaker volume L1 Set low speaker volume L2 Set medium speaker volume L3 Set high speaker volume M0 Turn Speaker off M1 Turn Speaker on during hand shaking and turn speaker ...

Страница 14: ...es are displayed in the single line format MS Select modulation ERROR CORRECTING COMMANDS C0 Disable data compression C1 Enable MNP 5 data compression C2 Enable V 42bis data compression Command Function C3 Enable both V 42bis and MNP 5 compression A0 Set maximum block size in MNP to 64 A1 Set maximum block size in MNP to 128 A2 Set maximum block size in MNP to 192 A3 Set maximum block size in MNP ...

Страница 15: ...Status T 0 S17 Reserved S18 Test Timer 0 255 Seconds 0 S21 V 24 General Bit Mapped Options Status 52 34h S22 Speaker Results Bit Mapped Options Status 117 75h S23 General Bit Mapped Options Status 62 3Dh S24 Reserved S25 Delay to DTR Off 0 255 Sec or 0 01 sec 5 S26 RTS to CTS Delay 0 255 0 01 seconds 1 S27 General Bit Mapped Options Status 73 49h S28 General Bit Mapped Options Status 0 S30 Disconn...

Страница 16: ...mponents are required to maintain conveyed FCC Part 68 approval for all HS Modems excluding the CH1799LL B For CH1799LL the required surge protection identified as D1 in dashed Box 2 must be supplied externally The purchaser must include some form of surge protection as described herein to maintain conveyed FCC Part 68 approval Refer to Application Note 130 for a list of recommended suppliers C In...

Страница 17: ...ent RST 500 µA Cp Capacitive Load TXD DTR RTS Capacitive Load RST 10 8 pF pF Test conditions VCC 5V 10 Temp 0 C to 70 F unless otherwise stated Output Load 50 pF one TTL Table 9 HS Modem Electrical Specifications Parameter Min Typ Max Units Comments Off Hook Impedance 20 Ohm Trans Hybrid Loss 25 dB 600 Ohm RXA TXA Ring Voltage Loop 110V 250V VPP On 48VDC line voltage for sustained periods Line Loo...

Страница 18: ...Approved UL 1950 Listed 0 C to 70 C CH1799ET Full Function 33 6kbps FCC Part 68 Approved UL 1950 Listed 40 C to 85 C CH1799LL Full Function 33 6kbps FCC Part 68 Approved UL 1950 Listed 0 C to 70 C CH1799TBR Full Function 33 6kbps FCC Part 68 Approved UL 1950 Listed TBR21 Compliant 0 C to 70 C CH1799ETBR Full Function 33 6kbps FCC Part 68 Approved UL 1950 Listed TBR21 Compliant 40 C to 85 C CH2056 ...

Страница 19: ... under any patents or patent rights of Cermetek Printed in U S A 406 TASMAN DRIVE SUNNYVALE CA 94089 LOCAL 408 752 5000 TOLL FREE 1 800 882 6271 FAX 408 752 5004 CERMETEK WEB SITE http www cermetek com EMAIL sales cermetek com iModem Network WEB SITE http www imodem net or https sunnyvale imodem net NOTES 1 All dimensions are inches 2 Case dimensions are nominal 0 02 inches 3 Pin length is nominal...

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