User`s guide

Introduction to the 34980A 1
Agilent 34980A Mainframe User’s Guide 7
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.
Alarm Limits
The 34980A has four alarms which you can configure to alert you when
a reading exceeds specified limits on a channel during a scan. You can
assign a high limit, a low limit, or both to any configured channel in the
scan list. You can assign multiple channels to any of the four available
alarms (numbered 1 through 4). For example, you can configure the
instrument to generate an alarm on Alarm 1 when a limit is exceeded on
any of channels 1003, 2025, or 3020.
You can also assign alarms to channels on the digital modules (34950A
and 34952A). For example, you can generate an alarm when a specific
bit pattern or bit pattern change is detected on a digital input channel or
when a specific count is reached on a totalizer channel. With the digital
modules, the channels do not have to be part of the scan list to generate
an alarm.
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 to 500
Thermistor 2-wire or 4-wire resistance from 10 to 1M
Pressure Solid state device ±10 VDC
Flow Rotary type, thermal type 4 mA to 20 mA
Strain Resistive elements 4-wire resistance from 10 to 10 k
Events Limit switches, optical counters,
rotary encoder
0V or 5V pulse train
Digital System status TTL levels