DeviceNet® Multi-Channel Temperature Sender

Project Description

Developed the hardware, firmware, and other details to provide the customer a completed, certified (UL, CE, and ODVA [DeviceNet® certification]), ready to manufacture product, that the customer is now selling.

The hardware includes switching power supplies, a highly integrated, state of the art PIC processor with CAN Interface, a 24bit A/D with a precision reference and I/O to control secondary functions of the device. Verifiable isolation of the system from the DeviceNet bus to the user’s “smart sensor” inputs also required the creation and use of custom magnetics and optocouplers that will meet the demanding timing criteria required by DeviceNet. Other areas of expertise are demonstrated in the ability to measure microvolt level signals from a thermocouple, even while in a relatively “harsh” EMC environment. The product was designed to fit in an off-the-shelf unshielded plastic enclosure that mounts directly on a DIN rail.

The firmware includes various device drivers for the hardware implemented (CAN Bus, A/D, misc I/O, Dallas One-WireÔ), in addition to the supervisory loop, and the definition and implementation of several DeviceNet standard objects with vendor specific extensions and attributes. DeviceNet communication includes Polled, Change of State, Cyclic and Strobed I/O messaging connections as well as explicit messaging. Assisted the customer to develop a DeviceNet EDS file to fully describe the DeviceNet characteristics of the product. The firmware also included definition and implementation of the IEEE 1451.4 specification for customer’s thermocouples and RTD sensors.

Debugged, tested and optimized firmware as required. Provided guidance in hardware testing and deployment for manufacture. Worked with software qualification personnel to provide verifiable operation of unit firmware.

Skills Required

  • System architecture knowledge.
  • System design to cost benefit analysis.
  • Knowledge of CAN and DeviceNet protocols.
  • Knowledge of IEEE-1451.4 for Transducer Electronic Datasheet (TEDS) (“smart sensors”)
  • Knowledge of the Dallas One-Wire protocol.
  • Orcad / Protel schematic / PCB Layout tools.
  • Mechanical packaging knowledge
  • Proficiency in ‘C’ language.
  • Knowledge of environmental controls.
  • Good organizational skills.

Services Used

  • Hardware design, and development.
  • Cost reduction / Compliance testing engineering.
  • PC board layout.
  • Design, coding, and debugging of functional modules for the system.
  • Documenting of hardware, software and test procedures.
  • Consulting with automated test equipment personnel as to functional test requirements.

Project Size

This medium sized project utilized a hardware and firmware engineer, in addition to client provided marketing, test engineering and other coordination personnel. Predicted unit sales volume – Initial: 1K/year, Expecting significantly more as the product matures.


  • Major manufacturer of industrial heaters and temperature sensors.
  • A local transportation refrigeration company.