User's Manual

11
Chapter 2
How Modem Mode
2.1 DIALING OUT
When the mobile computer is seated in the cradle, it can send the collected data back to
a remote server, as well as download lookup files, via GSM or 3G/GPRS.
When dialing out (ATDT), the LED of LAN will flash at the time interval of 0.3 seconds for
20 seconds. When connected, the LED of LAN will become green after successfully
establishing a connection. The LED of TX/RX will flash as long as data transmission
occurs.
Note: It is suggested to issue the command “AT” every five seconds for best practice, in
order to check whether the mobile computer is seated in the cradle.
The escape sequence, consisting of three characters “+++”, is used to terminate
the data connection.
2.1.1 GSM CONNECTION
When initialization is done, issue ATDT(phone number) to establish data connection via
GSM.
Note: GSM support is dependant on your Network operator and your ISP. Typically GSM
is used with 2G SIM cards.
2.1.2 3G/GPRS CONNECTION
When initialization is done, issue ATDTxxx.xxx.xxx.xxx:kkkk or ATDT[HostName:Port] to
establish data connection via 3G/GPRS. The buffer size of the cradle is 1460 bytes, and
data packet will be sent out as long as it satisfies any of the following requirements:
 buffer is full (= maximum packet size is 1460 bytes)
 delimiter character is encountered
 end of transmission timeout (= no transmission for 5 milliseconds)