Tech Blog

Modem Emulation

Sunday, 02 March 2014 23:26



Modem emulation assists in the transition from Circuit Switched Data (CSD) to Packet Switched Data/IP (PSD). If the control center management system supports IP but the field devices only support dialing back to the control center using CSD, then you can use the Intelimax to emulate the CSD modem interface. The Intelimax can also be configured to act as an IP stack server for incoming connections if necessary.

Dialing Process

From the perspective of the field device it will dial out a CSD data call like it always has, except the Intelimax will instead establish an IP stack client connection to the server. For example the field equipment may dial the following string: ‘ATDT0412123456’, then wait for the connection to be established by receiving a ‘CONNECT’ message. The Intelimax can be configured to establish an IP stack client connection to one of several different server IP addresses depending on the number dialed.

Intelimax Configuration

The Intelimax must be configured in IP stack auto server or IP stack manual server mode. This configuration can be made using the Intelimax GUI or via AT commands. If the Intelimax is in IP stack manual mode then it will only connect to the network when it receives the ATDT command via serial and will drop the connection when the call is hung up (+++, ATH). If the Intelimax is in IP stack auto mode (server) then it will act as an IP stack server (and therefore could be addressed remotely) until it receives the dial out commands.

Intelimax AT Command Configuration

The Intelimax modem emulation can be configured using the following AT commands:

To enable modem emulation and add a data number to IP address and port number emulation to the list

  • at$$emul=1,phone_number,IP_address,port_number
  • e.g. at$$emul=1,01044204414,,5000

To check current emulation list (must have already enabled emulation)

  • at$$emul?

$$EMUL: 1,3

To Enable/Disable Modem Emulation – this must be enabled on the server Intelimax for CONNECT message

  • at$$emul=0,0 – disable
  • at$$emul=0,1 - enable

To delete a rule from the list

  • at$$emul=2,list_number
  • e.g. at$$emul=2,1

$$EMUL: 1,2

Read 18766 times Last modified on Friday, 29 May 2015 09:02

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