Cellular Gateway

1.0. Overview

Historically, monitoring and control of remote sites required very little data bandwidth. Remote sites typically

had a few I/O and communicated over voice-grade phone lines. After the advent of PLCs and RTUs, many

remote operations had to improve communications to go along with the upgrade to these digital devices.

However, even PLCs and RTUs sometimes do not have enough data bandwidth to perform as needed.

Today, operators are asking for more capabilities in their remote operations, such as Video Surveillance and

remote Access Control.

In a modern control system with high speed networks, video surveillance for security, process control and

automation purposes can use the existing plant network to interface with Supervisory Control and Data

Acquisition (SCADA) systems and HMIs, such as Wonderware, Rockwell and GE Fanuc. However, many

control systems today do not utilize high speed networks and still communicate via slower connections.

While some video systems, such as the

Longwatch Video System, are designed

for low bandwidth networks, there are still

many remote sites, Figure 1, that have insufficient

infrastructure, obsolete technologies

or high levels of proprietary technology,

making it difficult for even Longwatch

to operate effectively. These include DC

telephone circuits, tone (FSK) communications,

proprietary radio networks, extremely

slow networks (300 bps), and others.

There is a very short and expensive list of

upgrade paths that will result in a network

that will be sufficient for video surveillance

applications. While all upgrade options

will require some level of engineering, the

simplest and fastest upgrade is to install a Cellular Gateway. With data rates up to 2 Mbps, a cellular connection

can handle most remote site communications needs.

The term Cellular Gateway refers to a device that acts as an interface between a control room computer or

LAN and a remote site through a cellular data connection. These gateways can provide high performance

wireless TCP/IP data communications via cellular networks for connecting remote sites and devices. This

communication pathway is secure and “always on,” allowing for on-demand transfer of data to both Ethernet

and/or serial devices. Setting up a cellular gateway is often simpler and much less expensive than installing

a point-to-point wireless system. Table 1 illustrates the main steps in configuring a Longwatch video

system via a cellular gateway.