Semiconductor Fabrication Control


A leading manufacturer of semiconductor fabrication equipment needed a way to communicate with a large number of serial devices from an industrial computer running their process control software. This customer preferred using the computer’s USB port but required isolation to protect the computer from potentially harmful voltage spikes present in their manufacturing environment. Sealevel leveraged our expertise in USB and serial connectivity to design a custom, isolated USB to 16-port serial solution designed to the customer’s specifications.

Application Requirements

  • 16 x RS-232 Serial Ports
  • Isolated USB Connection
  • Fast, Reliable Serial Communication on Multiple Ports Simultaneously
  • 24VDC Power Input
  • Private-labeled Appearance
  • 1U, 19” Rackmount Enclosure

The Sealevel Solution

Relying on our extensive experience in USB to serial solutions and custom chassis design, Sealevel delivered working prototypes meeting all functional requirements in only six weeks. The product was based on Sealevel’s unique USB to serial technology that provides faster, more reliable communications than UART-based solutions. The upstream USB serial connection was isolated using a Complex Programmable Logic Device (CPLD) along with high-speed digital isolators to protect against voltage anomalies (including ground loops) that can occur in industrial environments.

Key Design Challenge

Maximizing Data USB to Serial Throughput
Achieving fast, error-free operation via USB on 16 serial ports simultaneously required an alternative electrical design to the traditional UART-based architecture found in most USB-to-serial devices in order to eliminate the bottleneck between the microcontroller and the UART. Sealevel’s USB-to-serial design coupled each serial port with a dedicated USB UART chip. This design offers throughput equivalent to connecting 16 single port USB serial adapters to the host and allows each serial port to run at maximum speed.