Chapter 3 System Overview

Data Acquisition System Overview

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. 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.

Measurement

Typical Transducer Types

Typical Transducer Output

 

 

 

Temperature

Thermocouple

0 mV to 80 mV

 

 

 

 

RTD

2-wire or 4-wire resistance

 

 

from 5to 500

 

 

 

 

Thermistor

2-wire resistance from

 

 

10to 1 M

 

 

 

Pressure

Solid State

±10 Vdc

 

 

 

Flow

Rotary Type

4 mA to 20 mA

 

Thermal Type

 

 

 

 

Strain

Resistive Elements

4-wire resistance from

 

 

10to 10 k

 

 

 

Events

Limit Switches

0V or 5V Pulse Train

 

Optical Counters

 

 

Rotary Encoder

 

 

 

 

Digital

System Status

TTL Levels

 

 

 

Alarm Limits

The 34970A has four alarm outputs 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 103, 205, or 320.

You can also assign alarms to channels on the multifunction module. 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 multifunction module, the channels do not have to be part of the scan list to generate an alarm.

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Agilent Technologies 34970A manual Transducers and Sensors, Alarm Limits

34970A specifications

Agilent Technologies 34970A is a versatile data acquisition and measurement system that has gained popularity in various industries, including research and development, manufacturing, and education. The primary purpose of the 34970A is to offer an efficient solution for data collection, monitoring, and analysis, which can significantly enhance productivity and accuracy in testing applications.

One of the main features of the 34970A is its modular design, allowing users to customize the system according to their specific measurement needs. The mainframe can accommodate up to three plug-in measurement modules, which can include various types of measurements such as analog, digital, temperature, and frequency. This modularity provides flexibility for users to tailor the system to their requirements, making it highly adaptable to different applications.

Another notable characteristic of the Agilent 34970A is its impressive channel configuration. The system can support up to 120 measurement channels when fully configured, enabling extensive data acquisition without the need for multiple devices. This capability is essential for applications requiring simultaneous monitoring of multiple parameters or locations.

The 34970A utilizes advanced signal processing technologies to ensure high-accuracy measurements. The internal 6.5-digit resolution multimeter provides precise readings, while the device also supports various input types, such as thermocouples and RTDs for temperature measurements. The ability to perform mathematical functions, such as summation and averaging, on the acquired data further enhances its usability.

For data storage and management, the Agilent 34970A features built-in memory for storing up to 20,000 readings. Users can also easily transfer data to a PC through the RS-232 interface or GPIB (IEEE 488) for further analysis and reporting. Additionally, it offers the capability to program automatic data logging and scheduling of measurements, which streamlines the testing process and reduces manual intervention.

In terms of user interface, the 34970A is equipped with a large graphical display that provides clear visualization of measurement data and easy navigation through settings and options. The menu-driven interface makes it accessible for users of all skill levels, simplifying the setup and operation of the device.

Overall, the Agilent Technologies 34970A stands out for its modularity, high channel capacity, advanced measurement technologies, and user-friendly interface. As a reliable and efficient data acquisition system, it is well-suited for a wide range of applications, making it an essential tool for engineers and technicians looking to enhance measurement precision and efficiency.