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r Pro v3.0

4.18

InitStrings

What is an init string?

Different modems  can t necessarily  talk to each  other as  set right out of the box.  Modems  use  many different

settings  and protocols.   In order for two modems  to communicate,  they must  agree on many things  such  as

speed,  error correction,  compression  algorithms,  etc...  By sending  a modem  an init  string, you can control

some  of these  parameters.

What do I need to put in my init string?

In general,  the modems  used  by paging  carriers  run at a speed  from 300 to 2400 baud (1200  being the most

common).   They don t typically use  any form of error correction  or data compression  protocols.   In many cases,

if your modem  tries to use  either of these  protocols, your modem  will  be unable  to communicate  with the

paging  terminal s  modem.   In your init string  you should  lude  settings  to lock you modem s  baud rate to that

of your carrier s  modem,  disable  error correction  protocols,  and disable  data compression  protocols.   In

addition  r  Pro would  like  your modem  to issue  English  response  codes  (rather than numeric

response  codes),  and issue  complete  connection  information.

Do all modems use the same init string?

No, many different  modem  manufacturers  use  their  own set of modem  commands.   Init strings  may even be

different between  models  by the same  manufacturer.

My init string works  on one carrier  but not the other.

You may need a different  init string to connect  to each  carrier.  In general your init strings  will  be the same,  but

not always.

What init string should I use?

There is  no easy answer  to this.   In general,  if your modem  is a 2400 baud model  or slower  (very old models)

you won t need an init string.   These  older modems  sometimes  work best when  communicating  with the

paging  terminals.   Anything faster  (9600, 14.4, 28.8, 33.6, 56K, etc.), will probably  require an init string.   Some  of

the most  common  init  strings  are listed  below.  If you have a less  well  known brand modem,  you may need to

use  the documentation  lude  with you modem  to create an init string.

Common Init Strings

AT&FQ0V1X4&D2     Minimal settings.   Works  with most  1200 and 2400 baud modems.  Some  modems  use

&F0 rather than &F.  All  0  are zeros not oh s.

AT&FQ0V1X4&D2N0S37=5     Hard coded  baud rate.  Works with many 14.4 and 28.8 modems.   The added

codes  locks  the connection  baud rate to 1200 baud.   Use  S37=3 for a 300 baud connection,  and S37=6 for a

2400 baud  connection.   Some  modems  use  &F0 rather than &F.  All  0  are zeros not oh s.

AT&FQ0V1X4&D2N0S37=5\N0%C0      No  compression/error  correction.   Works with many 14.4, 28.8 and 33.6

modems.   The added  codes  turn off data compression  and error correction.   You can try using  only one of the

two additional  codes  (\N0 or %C0)  if you modem  rejects  using  both.  Use S37=3 for a 300 baud connection,

and S37=6 for a 2400 baud connection.   Some  modems  use  &F0 rather  than &F.  All  0  are zeros not oh s.

AT&F0Q0V1X4&D2&B1&K0&M0&N2     US Robotics  (3Com) string.   Works  with most  US Robotics/3Com  33.6

and 56K modems  (and some  others too).  Use &N1  (instead  of &N2)  for a 300 baud connection,  or &N3 for a

2400 baud  connection.

AT&FQ0V1X4&D2N0+MS=B103    This string has  been  found to work with some  of the newer  winmodems.   Set

the baud rate to 300 when  using  this  string.

Note: all  0  characters  in the init strings  are zeros not oh s

***More init strings  may be available  on our web site:  www.r.com

   ,  .