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Project Overview

The following is a brief overview of the project, including Motivation and Requirements.

Motivation

A common problem with data acquisition systems is that it can be difficult to obtain the signals required to fully test the system, whether during design, manufacturing, or field testing. First, it is difficult to obtain the full range of sensor output data values in the field because the conditions they represent may not be duplicable. For example, it would be difficult to aquire the full range of outputs from a temperature sensor in Victoria, where the temperature does not vary greatly. Second, some sensors are not readily available in the lab, or are too costly to obtain solely for testing purposes.

These issues are of particular concern to AXYS Environmental Systems, who specialize in the design, manufacture, and installation of environmental monitoring systems. Their systems acquire data from environmental sensors and output readings as current, voltage, pulse frequency modulated (PFM) signals, or as RS232 test messages. To ease the testing of these environmental monitoring systems, a single unit that could provide simulated sensor outputs would be of great benefit.

Taking into account that each type of sensor produces its own unique combination of signals, there are several types of signals that are commonly found in industry. It would increase the accuracy and efficiency of data acquisition system testing if these common signal types could be generated in a time-varying fashion by a single test unit. The goal of this project is to design a system that would be capable of generating these signals, based on user configuration.

requirements

The following is a brief summary of the requirements for the Programmable Sensor Output Simulator project. For more details, please see Final Project Specifications under Documents.

System Description

The system will consist of a hardware instrument, controlled by a Microsoft Windows based PC via a Graphical User Interface (GUI). Using the GUI, a user can create a configuration for the instrument, indicating the specifics of the time varying signals it is to generate. The user can then load the configuration to the instrument, and control the instrument via an RS232 connection.

Three types of sensors outputs are to be supported. They are:

  • Analog Voltage / Current - 6 Channels
    • 14 bit precision
    • 3 ranges: ±2.5V, ±5V, 4-20 mA
    • the instrument will output values that are linearly interpolated from user defined data points
    • maximum refresh rate will be 8 KHz
  • Pulse Frequency Modulation - 2 Channels
    • Frequency: 0.1 Hz - 100 kHz at 50% duty cycle
  • Serial RS232 Outputs - 4 Channels
    • ASCII messages with up to 25 user definable fields including the following field types
      • static text
      • varying number (integer or floating point)
      • date/time (user specified format)
      • blank
    • User definable start, end, and delimiting characters
    • Baud Rate: 300-38400 bps standard
    • Optional 1 byte XOR checksum

Project Deliverables

The following are the expected deliverables for this project:

  • Hardware design and documentation
  • Firmware design and documentation
  • Software (GUI) design and documentation
  • Documentation for producing multiple units
  • Project Final Report

 

Last Updated: April 8, 2005   

 

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Sponsored by:

UVic Engineering AXYS Technologies