1
Introduction to the 34980A
20
Keysight 34980A Mainframe User’s Guide
Transducers and Sensors
Transducers and sensors convert a physical quantity into an electrical quantity.
The electrical quantity is measured and the result is then converted to engineering
units by the 34980A's main system processor. For example, when measuring a
thermocouple, the instrument measures a dc voltage and mathematically
converts it to a corresponding temperature in °C, °F, or K.
Cable Type
Common Uses
Comments
Thermocouple
Extension Wire
Thermocouple
measurements
Available in specific thermocouple types.
Also available in a shielded cable for added noise immunity.
Twisted Pair,
Shielded Twisted
Pair
Measurement inputs,
voltage outputs,
switching, counting
Most common cable for low-frequency measurement inputs.
Twisted pair reduces common mode noise. Shielded-twisted
pair provides additional noise immunity.
Shielded
Coaxial,
Double-Shielded
Coaxial
VHF Signal switching
Most common cable for high-frequency signal routing.
Available in specific impedance values (50
Ω
or 75
Ω
).
Provides excellent noise immunity. Double-shielded cable
improves isolation between channels.
Requires special connectors.
Flat Ribbon,
Twisted Pair
Ribbon
Digital Input/Output
Often used with mass termination connectors. These cables
provide little noise immunity.
Measurement
Typical Transducer Type
Typical Transducer Output
Temperature
Thermocouple
0 mV to 80 mV
Resistance temperature detector (RTD)
2-wire or 4-wire resistance from 5
Ω
to 500
Ω
Thermistor
2-wire or 4-wire resistance from 10
Ω
to 1M
Ω
Pressure
Solid state device
±10 VDC
Flow
Rotary type, thermal type
4 mA to 20 mA
Strain
Resistive elements
4-wire resistance from 10
Ω
to 10 k
Ω
Events
Limit switches, optical counters, rotary
encoder
0V or 5V pulse train
Digital
System status
TTL levels