Motorola V186 - Cell Phone - GSM System Planner Manual page 118

Communications
MDLC over GPRS Network
An RTU can be connected to GPRS (GSM) network through a LAN or through a radio.
An IP Gateway or an RTU with an Ethernet port can be connected to the LAN.
In the figure below, the SCADA central and IP Gateway are connected via LAN to the
GPRS infrastructure. Each RTU has a G18 GPRS/GSM modem connected to its MDLC
over IP Port using PPP. A unique IP address is assigned to each RTU according to its
modem identifier (IMSI). All communication between the RTUs and the IP Gateway
involves sending datagrams in packets. The GPRS infrastructure routes those packets
directly between two RTUs, or between IP Gateway and an RTU. A PC running STS can
be connected directly to an RTU or operate remotely over IP.
SCADA
Central
Ethernet
RTU
IP
Gateway
RSlink1
g18 GPRS
Packet Data
modem
GPRS
infrastructure
LINE 1
g18 GPRS g18 GPRS
Packet Data Packet Data
modem modem
RS-232 RTU-A RTU-B
STS
A single GPRS modem can be connected to an RTU. Other ports can be connected to
other GSM modems using dialup ports.
It is recommended that the operator provides an APN (Access Point Name) for a fixed IP
address and enable one modem to communicate with another over UDP port 2002.
However it is not always possible, so the following steps can be made:
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