Process Temperature Maintenance


Certain process control applications require exposing electronics to harsh environments such as extreme temperature, vibration, water, or chemicals. Using a Human Machine Interface (HMI) in extreme temperatures can be problematic since most HMIs are based on TFT LCDs that cannot be operated without damage below 0°C without a heating system. Sealevel worked with a customer that makes equipment and wiring for process heat maintenance on a requirement for a rugged, economical HMI that operated to -30°C. Sealevel’s engineering team overcame this challenge by designing an LCD-based HMI capable of operation below 0°C without heaters.

Application Requirements

  • 8″ or 10″ TFT LCD with Touchscreen
  • Ethernet Connectivity
  • Minimum 2 Open-Collector Outputs
  • Minimum 2 Isolated RS-485 Ports
  • Powered from 24VDC
  • NEMA 4/IP65 Mounting Bezel
  • Private Label Packaging
  • Software Imaging for Production Systems

The Sealevel Solution

Since the use of Cold Cathode Fluorescent Lamp (CCFL) backlights results in the 0°C minimum operating temperature limitation of most standard LCDs, Sealevel sourced an 8.4″ TFT LCD that uses newly developed LED backlighting capable of power on at temperatures as low as -30°C without decreasing the lifespan of the display. A customized version of Sealevel’s wide temperature SBC-R9 board provides RISC computing running under Windows CE 6.0 in a .NET environment to the system. Now sold as a standard Sealevel product called SeaPAC R9, the system includes a machined aluminum front bezel that maintains NEMA 4/IP65 standards for protection from liquids.

Key Design Challenge

Incorporating New LCD Technology into a Rugged HMI Design
The SeaPAC R9 design required a combination of electrical and mechanical expertise to interface the new 8.4″ LCD and resistive touchscreen. To exactly match the customer’s I/O requirements, Sealevel created a new version of the Relio R9 industrial computer to provide the correct mix of I/O and the necessary metal assemblies to meet the NEMA 4 requirement. Custom length video and touchscreen cables were created for the system, and a watertight, attractive bezel assembly was designed for panel mounting. To establish the customer’s unique brand identity, the bezel was customized with a color overlay that includes the name of the end product and our customer’s logo.