Data Logger - For Monitoring Environmental Conditions

This project is to make a device capable of reading multiple analog sensor values and storing them in a database. The data can then be analysed or plotted on graphs to show how certain variables change over time.

The main interface between the sensors and the computer system is Veleman K8055 USB Experiment board. This board has just two analog inputs, but a simple circuit similar to the DIY Sensor Multiplexer will be used to make it able to read from up to 16 analog sensors.

Most of the time on this project will probably spent on developing the software to control the device. The software will be a windows based application and it will not only log sensor information, but will upload the data to the web site so that it can be viewed by all.

Last Update : April 2^nd 2007

You can see the previous projects in the DIY Devices section.

Progress Updates

02/04/07 - Latest

Not much practical progress since the last update. A new multiplexer has been designed, and we are awaiting the finished PCB's. The new multiplexer has 10 channels, each with an independantly adjustable differential amplifer, a built in timer, and a few other extra features. The addition of the amplifiers will reduce the need for additional circuitry for each individual sensor. The new design can also be daisy chained if more channels are needed.

04/02/07

The software now outputs a formatted csv file, containing data from all 8 multiplexed inputs. The poll, hold, and upload times can be set for optimum use. The software currenlty generates a single file, and continues to update it at the selected interval. This will need to be changed so that the data is broken across several timestamped files.

The PHP code for generating grapghs has been setup in a basic format. it is powered by the open source software known as GraPHPite. Once the PHP code has parsed the data file, it passes the numerical data to GraPHPite so that it can generate images.

15/11/06

The program has been set up for multiplexing just 8 sensors on one port as 16 is not really necessary. This leaves one ADC free which can also be read 8x faster than any other sensor. The sensor multiplexer from the DIY PC Robot has been recycled for use with this project for now.

The software is also now recording the data to a file and uploading it to the web automatically. This data needs some formatting as its just a stream of numbers at the moment. The next thing would be to create the software for generating graphs to be sent or generated on the site.

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14/06/2006

A basic working program has been produced that controls the multiplexing and sensor data capture from 16 inputs.

The current multiplexer circuit is only functional for a few extra inputs, but the software is ready and capable of controlling all 16.