Terminology » Components » Class 1 vs. Class 2 TEDS Sensors: Key Differences

Class 1 vs. Class 2 TEDS Sensors: Key Differences

sensor teds class 1 class 2 transducer

This article highlights the differences between Class 1 and Class 2 TEDS (Transducer Electronic Data Sheet) sensors as defined by the IEEE 1451.4 standard.

Introduction:

TEDS, an acronym for Transducer Electronic Data Sheet, is a standardized approach (IEEE 1451.4) for “plug and play” functionality of analog transducers. This standard specifies the crucial information needed by a measurement system to identify, characterize, and interface with analog sensor signals. TEDS provides a standard way to store key sensor, transducer, and actuator information.

Essentially, TEDS eliminates the need for manual sensor setup by embedding vital data within the sensor itself. This ensures correct settings are applied automatically.

A TEDS-enabled sensor houses non-volatile EEPROM containing information such as:

  • Sensor type or class
  • Serial number
  • Model name
  • Calibration data
  • Manufacturer name

There are two primary ways to implement TEDS: Class 1 and Class 2, which we’ll explore below.

Class 1 TEDS Sensor

Class 1 TEDS Sensor Image Alt: Class 1 TEDS Sensor

  • Shared Line: As shown in Figure 1 (above), Class 1 sensors use a single line for both the analog signal and the digital TEDS signal. This is achieved through multiplexing based on sensor biasing.

  • Switching Circuit: These sensors require an EEPROM and a switching circuit, dependent on the bias direction.

Class 2 TEDS Sensor

Class 2 TEDS Sensor Image Alt: Class 2 TEDS Sensor

  • Separate Lines: Figure 2 (above) illustrates that Class 2 sensors utilize separate lines for the analog signal and the digital TEDS EEPROM signal.

  • No Switching Circuit Required: This eliminates the need for a switching circuit since analog and digital TEDS signals are transmitted independently.

Summary of Key Differences

The primary difference lies in how the analog and digital signals are handled:

  • Class 1: Uses a single, shared line for both signals, requiring multiplexing and a switching circuit.
  • Class 2: Uses separate lines for each signal, simplifying the design and eliminating the need for a switching circuit.