MODEM EMULATION WITH INTELIMAX
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.
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.
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.
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
To check current emulation list (must have already enabled emulation)
To Enable/Disable Modem Emulation – this must be enabled on the server Intelimax for CONNECT message
To delete a rule from the list
The Maxon Intelimax modem has the unique in-built feature of being able to change between modes and configure settings remotely over a CSD call. This is especially useful if you have a modem in the field that you need to remotely configure using remote AT commands or the Intelimax GUI but are currently using CSD to talk to this modem. Using these commands lets you change to an IP connection for easy access to the device over an IP connection. This feature is available from firmware versions 0.1.67 onwards.
It is very important to ensure that you can access your modem once this is done which means either using a static IP address (private IP WAN or similar) or a public dynamic IP address such as telstra.extranet the WAN IP of which can be found via SMS.
Dial out to the modem via a command line terminal session to your data modem using the data number of the SIM card in the Intelimax. The sting will be as follows: ATDT0400123456. Once the ‘CONNECT’ message has been displayed you are connected.
Intelimax Remote Configuration Commands
The following commands can be used to change the settings of the Intelimax:
1- IP Stack Auto mode –auto connect IP
2- IP Stack Manual mode –manual connect IP
3- Serial modem mode –for CSD or when end device controls connection
Apply all the settings and reboot: program.maxon.lock
Once the commands have been received by the modem it will display ‘Modem will reboot now’ and the call will be dropped as the modem reboots:
Once the modem reboots (approximately 2 minutes) if a public dynamic IP address has been used it can be found using the following SMS to the phone number (not data number) of the SIM in the modem: