EnFlex used embedded Linux in an industrial control and monitoring system targeting facilities management. The Site Control Server (SCS) G100 is based on a 586-class processor and runs Debian Linux. Its web interface can integrate and manage multiple serial- and Ethernet-based facilities control systems, according to the company.

SCS G100 (Click to enlarge)

Uses for the G100, according to EnFlex, include:

• Integrating third-party devices
• Linking separate energy management systems
• Distributed generation monitoring and control
• Intelligent demand limiting and load curtailment
• Common enterprise facility gateway
• Web-enabling facilities controls
• Real-time metering
• Environmental and tank monitoring
• Advanced lighting and HVAC control
• Data logging and trending
• Wireless network management

The company says the G100's web-based interface requires less training than the client-side, Windows-based control application bundled with previous models of its SCS products. In addition to a web interface, the G100 offers local monitor and keyboard ports for “local control functions, status display, troubleshooting, configuration, and troubleshooting of connected devices.”

The G100 comes with a library of device drivers said to support a wide variety of third party facilities control systems and devices. Also included are “EnFlex Connect” and “EnFlex Script” packages aimed at helping users create drivers for other third-party devices that attach via RS-232, RS-485, or Ethernet.

The G100 supports a variety of TCP/IP protocols, including HTTP, SLIP, PPP, SNMP, and NFS, as well as a range of TCP/IP services, such as FTP, Telnet, and more, the company says.

What's under the hood?

The EnFlex G100 is based on an off-the-shelf 500 MHz 586-class SBC (single-board computer), with “special cables and enclosure developed for the SBC by EnFlex,” according to David Wolins, VP of business development. From its appearance the SBC seems to be an Advantech 5820, a “3.5-inch biscuit SBC” that's based on a National Semiconductor Geode GX1 processor.

Inside view of the SCS G100 showing the embedded SBC
(Click to enlarge)
The G100 comes standard with 64MB of RAM, and 32MB of flash memory. Larger configurations are available, although the stock configuration does leave some room for user applications, the company says.

In addition to local VGA monitor and keyboard ports, I/O interfaces include 10/100 Ethernet, and two serial ports for connecting legacy control systems. Expansion is available through optional PC/104 modules, as well as through optional USB ports. Optional “3 pulse counter inputs” are also available.

The G100 is housed in an aluminum case measuring 5.8 x 8.1 x 2.4, and can operate at temperatures up to 60 degrees, Celsius. It requires a 5-volt power supply, and comes with an external regulated power supply that plugs into “any 120VAC outlet,” the company says.

Debian Linux implementation

According to Wolins, the G100 runs a 2.4.27-10sarge1 Debian kernel, along with a Linux filesystem based on Debian 3.1r1, with the latest security updates applied. In addition to “common Linux utilities,” interesting open source applications used include Apache, perl, and TCL 8.4, Wolins says.

Previous incarnations of EnFlex's SCS were based on Red Hat 4.2, Wolins notes, and provided a network interface through a Windows client application, rather than a web-browser interface. The most difficult part of the Linux upgrade process, according to Wolins, was in creating the needed web pages, and in porting proprietary applications to a much more modern Linux distribution. “The primary challenge was in porting our proprietary application from using libc5, gcc 2.7, and MIT Pthreads to using glibc, gcc 3.3, and either Linuxthreads or NPTL.”

However, despite the many years difference between the previous and current SCS Linux platforms, much about Linux has remained unchanged, Wolins observes. “It is obvious that many things have changed with newer distributions, however GNU/Linux has pretty much 'stayed the course'
in the progressions from Red Hat 4.x to the newer Debian 3.1,” he said.

EnFlex has used Linux in its products since 1995, according to Wolins.

Availability

The SCS G100 is currently shipping “to select customers,” Wolins says, but will be generally available in July, 2006.

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