OEM Cellular Data Modem
CM 900

wireless dial modem access solution- (looks and feels like a standard RS 232 AT command compatible modem)
VDC power / -20 to + 75 C. temp rating option

This low cost combination of a modem & cell phone is ideal for those
" remote remote" sites where a phone line is impossible.

With the cost cellular service declining a cellular modem makes sense for gas and electric meters.

The CM 900 is designed around the Radio CRM 4100 from Standard Communications. Once interfaced with the 4100, to the user, the entire module looks like a standard RS 232 AT command compatible modem. This allows compatibility with popular software packages like Procomm, Hyper terminal, Bitcom, WinFax etc.

Cellular Data Modem "OEM" CM 900

 

Features

Sample Application Areas

Cellular Data Modem CM 900

Specfications

 

Your package includes:

SIZE
4 7/8" mid hole to mid hole
5 1/2" end to end
3" from outside data connector to outside of power connector
1" thick

jump to PDF file of manual

jump to DOC file of manual

Base Station Omni Antenna
jump to cellular base station antenna PDF file
(prices are for antenna only)

OD4-900 4db gain $105.00
OD5-900 5db gain $195.00
OD6-900 6db gain $245.00

Base Station Yagi Antenna
jump to cellular Yagi high gain antenna PDF file - (prices are for antenna only)

YAG6-900 T or N  6db gain $75.00
YAG9-900 T or N  9db gain $75.00

jump to Magnetic mount antenna page

jump to Mobil antennas

 

Optional - CM 900 with out Radio unit - for use with external cell phone

What you need to provide:

Installation:

The CM900 is configured as a DCE (e.g. modem). It talks to a PC through the RS 232 cable.                                                                                                                 

  1. Remove the screws from the top of the spacers
  2. Mount the CRM 4100 radio to fit into the 20 pin female header
  3. Connect the screws on the spacers
  4. Connect the power supply. Please take caution in making sure that the voltage with correct polarity only is applied. The LED should be on and current less than 500 ma.
  5. Connect the RS 232 cable provided. Connect the Antenna.
  6. The unit is ready for operation.

First Time Quick Start

For a typical session, the following may help.

Connect the CM900 (with the CRM 4100 radio) to the PC. Configure the serial port to 9600 bps, 8N1 and Hardware Handshaking.

Power up the unit.

Allow 10 seconds for calibration.

Enter <CR>. This allows the unit to auto-baud to match the speed of the PC.

The CM 900 will respond OK. This exercise must be repeated every-time on power up.

We are now ready to configure the radio.

1)    Enter AT+TEST<CR>. The unit will respond OK.

2)    Enter AT+MIN=< the MIN allocated><enter> The unit will respond OK.

3)    Enter AT+SID=< the SID allocated><enter> The unit will respond OK

4)    AT+SYS=02 <CR> The system is set for normal mode.

The radio is now configured and ready for operation.

Please note that radio does NOT have to configured every-time. The above information is stored in the Radio’s non-volatile memory.

Operation:

The CM900 (here after referred to as the modem) is always in one of the two states: the command state or the on-line state. The modem assumes the Command State when power is applied. This state allows the modem to be configured for the particular application. In the Command State, all inputs from the PC are treated as commands . The modem may be set to the on-line state in which all inputs form the PC are treated as data to be shipped over the airwaves and all inputs from the airwaves is treated as received data from the remote end.

Command guidelines

Command lines must begin with the characters AT and end with Carriage Return (CR). Either all upper case or all lower case characters must be used.

Command Buffer

The command buffer is 40 characters.

Each command must be entered separately.

Result Codes

Result codes are responses by the modem to commands. These are shown below:

   Code              Digit Word Code Meaning

 

     0                    OK Command executed without errors.

     1                    CONNECT Connection at 300 bps

     2                    RING Ringing signal detected

     3                    NO CARRIER Carrier lost or never present

     4                    ERROR Invalid command

     5                    CONNECT 1200 Connection at 1200 bps

     6                    NO DIAL TONE Cellular service not available

    7,8                 not used

     9                    SERVICE UNAVAILABLE Cellular service is not available.

    10                  No communication is possible

    11                 SERVICE AVAILABLE Unit ready for communication

 

On-line state

The Modem is in on-line state in one of the two conditions:

  1. The user dials out and a successful connection is made.
  2. An incoming call is answered and a successful connection is established.

When the modem is in on-line state, all serial data presented to the radio is transmitted over the air.

Do NOT change communication parameters (e.g. baud rate) in this mode.

To go back to Command State, Escape Sequence (described in this section) is required.

Escape sequence

The sequence of characters to transition from On-line State to the Command State is called the escape sequence.

The sequence is +++

The timing interval between the + signs must be between 250 msecs and 750 msecs.

On receipt of a valid escape sequence, the modem will enter Command State and respond with OK.

Supported AT commands

The basic AT (ATtention) commands used to configure the modem operation are defined in this section. The commands implemented are a subset of the commands used in typical high-speed modems.

Upon power up, the user must enter <CR> <CR> ( carriage return twice ). This allows the modem firmware to detect the RS232 baud speed.

A command line is a string of characters sent from the DTE (e.g. a PC) while the modem is in Command State. A command line has a prefix, a body and a terminator. Each command line must begin with a character sequence AT and must terminate with a carriage return.

The Radio starts the processing of commands only after AT string sequence is received.

Commands entered with out of range parameters will result in ERROR message.

Correct commands will result in OK message.

Following AT commands are supported:

Command                                       Action

1)    ATZ<CR>                              Resets the modem.
                                                      The unit will respond a with initializing message
                                                      And then OK

2)    ATO<CR>                              Go on line.
                                                       This is done after the state of the unit is changed from
                                                       on-line to command state. 
                                                       ATO then puts the unit back into on-line state.

3) ATDT XXXX <CR>                  Cell modem dials out. XXXX(phone number)

4) AT+SYS=xx<CR>                     Sets system preference.
                                                        (SYS =00  Sets the unit for system B only)
                                                        (SYS =01 Sets the unit for system A only)
                                                        (SYS =02 Is for normal mode. SID determines preferred system)
                                                        (SYS =03 Is for home use only)

5) AT+RSSI?<CR>                        Indicates the Received Signal Strength.
                                                        Higher the better. Should be > 10H for reliable communication.

6) AT+SERVICE?<CR>               Indicates if service is available or not

7) AT+TEST<CR>                        Puts the unit to test mode.

The next three commands are accepted Only after the unit is put into test mode.

8) AT+MIN=XXXXX<CR>          Sets the MIN number. The modem responds OK

9) AT+SID=XXXX<CR>              Sets SID. Modem responds OK

10) AT+ID?<CR>                          Displays ESN, MIN, SID,

System Preference information.

Note: MIN, ESN, SID information are stored in the non-volatile memory of the cell-modem. These do not have to be entered every-time on power-up.

11) AT+BAT?<CR>                     Indicates battery level in hex format.
                                                      00= zero and 64 H = 100%

12) AT&V<CR>                            Displays settings of the cell modem

13) ATI3<CR>                              Displays Software Revision #

14) ATH0                                      Modem disconnects and initializes

15) ATV0                                      Unit responds in terse mode. Results code Displayed as digits

16) ATV1                                      Unit responds in verbose mode. Results codes
                                                      are displayed as messages.

Escape Sequence:

When the modem is on-line state, it is possible to break the data transmission/reception.

This is achieved by sending a sequence of three ASCII characters. For ease of use, the

default character is +. The Radio will respond with OK on detection of valid escape sequence.

17) +++ Escape sequence OK

Quick Troubleshooting Hints:
  1. If the unit draws too much power. Please ensure that the power supply is correctly wired.
  2. If dialing out is repeatedly unsuccessful and modem gives the message "NO DIAL TONE ", please check if service is available.
  3. If the unit never connects on dialing out, please ensure that the ESN (Electronic Serial Number) is the proper one for the MIN number allocated.
  4. Please check RSSI level. If low, placing the antenna vertical will help.
  5. If remote landline modem connection drops frequently, please have the calling party set S10 register to 100. This will make the modem more tolerant of noise hits.

     

     

    ARC ELECTRONICS
    a DCE Company

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