User`s manual

SMG-1100/6100 Introduction
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Configuring IPSec Tunnels
To set up IPSec tunnels between the SMG-6100 and the remote mobile SMG (the SMG-1100), refer to the
VPN(IPSec) section in the SMG Manager chapter of this manual. We strongly recommend that IPSec tunnels
be configured from the SMG-6100 and deployed to the SMG-1100 at the same time via SMG Managerat the
local site. When finished, the SMG-1100 can be moved to the remote field site.
Introduction to MODBUS Gateway
The Moxa SMG-1100 is a secure mobile MODBUS gateway that provides IPSec tunnels between itself and the
peer IPSec Gateway SMG-6100 via the Internet while transferring MODBUS messages. It features two
RS-232/422/485 serial ports, one 10/100 Mbps Ethernet port, and a GPRS/EDGE wireless module for mobile
connections.
MODBUS Gateway Applications
MODBUS TCP Master
In the MODBUS Gateway configuration for a MODBUS TCP master and MODBUS RTU/ASCII slave, programs
running on the MODBUS TCP master can securely send MODBUS TCP request messages via the Internet to the
MODBUS TCP slave. The MODBUS Gateway then sequentially converts MODBUS TCP request messages to
MODBUS RTU/ASCII messages and sends the request messages to connected MODBUS RTU/ASCII slave
devices through the serial port, based on specified slave ID values in the MODBUS request messages and
settings in the MODBUS Gateway. When the slave devices receive MODBUS RTU/ASCII request messages, they
reply with MODBUS RTU/ASCII response messages to the MODBUS Gateway. Once the MODBUS Gateway
receives MODBUS RTU/ASCII response messages, they are converted to MODBUS TCP response messages and
sent to the corresponding programs of the MODBUS TCP master.