Description of Controls
057-233 ISSUE: 1 Page 52 of 90
Module Connected To an RS232 GSM Modem
NOTE: Not all alarms generate a dial out command; this is dependant upon module
configuration of the event log. Any event configured to be recorded in the event log causes the
modem to dial out to a PC.
NOTE: In the case of GSM modems, it is important that a DATA ENABLED SIM is used.
This is often a different number than the ‘voice number’ and is often called Circuit Switched
Data (CSD) by the SIM provider.
When the module is powered up, it sends ‘initialisation strings’ to the connected modem. It is
important therefore that the modem is already powered, or is powered up at the same time as the
module. At regular intervals after power up, the modem is reset, and reinitialised, to ensure the
modem does not ‘hang up’.
If the module does not correctly communicate with the modem, “Modem initialising’ appears on the
Serial Port instrument screen as shown overleaf.
If the module is set for “incoming calls” or for “incoming and outgoing calls”, once the modem is
dialled, it answers after two rings (using the factory setting ‘initialisation strings). Once the call is
established, all data is passed between the dialling PC and the module.
If the module is set for “outgoing calls” or for “incoming and outgoing calls”, then the module dials out
whenever an alarm is generated.
Many GSM modems are fitted with a status LED to show operator cell status and ringing indicator.
These are a useful troubleshooting tool.
In the case of GSM connection problems, try calling the DATA number of the SIMCARD with an
ordinary telephone. After two rings, the modem answers the call and then starts ‘squealing’. If this
does not happen, check all modem connections and double check with the SIM provider that it is a
DATA SIM and can operate as a data modem. DATA is NOT the same as FAX or GPRS and is often
called Circuit Switched Data (CSD) by the SIM provider.
Press the Scroll Down button view the modem GSM
status....
If the GSM modem is not purchased from DSE, ensure that it has been correctly set to operate at
9600 baud.
Currently connected GSM
operator and signal strength.
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