Requirements

Currently there does not exist a coupler to connect a standard 4-20mA loop sensor to a digital interface. This project will solely focus on building the coupling device because sensing and transmitting solutions already exist in the marketplace. The expected outcome of the capstone project is to be able connect a standard 4-20mA loop sensor to a Geoforce transmitter via I2C or Bluetooth with minimal power consumption, a low error rate, and integrated fault detection. The solution will have to be portable, last for 5 years, and survive in a rugged environment.

Level 1

Multiple different requirements were set forth as the criteria for success after the initial meeting with Geoforce. These are the level 1 requirements for the device and are as follows:

  • Sense 4-20 mA on twisted pair interface with 10 bit accuracy
  • Survive on 4 Lithium Primary Cells (3.6V each) for 5 years with 2 measurements per day
  • Communicate data (16 bit packet) over I2C (or Bluetooth) to standard Geoforce transmitter
  • Include fault detection
  • Have better than 95% accuracy overall (from sensor to transmitter)
  • Fit inside the volume of Geoforce’s GT1 transmitter
  • Cost less than $50 in parts to build at a quantity of 10,000 units

EELE 488