Data Acquisition Over The Net
Low cost, remote measurement can now be realised through PC-based instrumentation and IP networking. Mike Green, MD of Pico Technology, explains further.
Figure 1: EnviroMon, Pico Technology’s software for its standalone data logging products, features Internet Protocol (IP) networking capability. In addition, PicoLog (software for PCs used in data-logging applications) is also IP capable — enabling remote data collection from the company's full range of data acquisition products.
Since the early days of electronics, data acquisition and signal conditioning have enabled us to measure quantities — such as temperature, light levels, voltages and currents — and represent them in a meaningful format. Moreover, we have been able to use electronic data acquisition and data logging to capture data in remote locations, either by leaving standalone equipment and collecting the data periodically, or by using expensive wired or radio links.
Until recently, however, data acquisition and logging have required custom hardware and software solutions, and these have been prohibitively expensive for all but high end applications.
In the early 1990s, PC-based instrumentation appeared on the scene and data logging changed forever. Data acquisition — which had been bespoke, specialist and expensive — started riding on the back of the PC industry, which meant that it could reap the benefits of low cost and standardised user interfaces.
The demand for remote measurement and data acquisition, in not only factories but also office buildings, is perhaps greater than you might imagine. What is the humidity in the PC server room? What is the temperature in the production department? Which doors are open and which are closed?
Remote Measurement
Many office premises (some of which are listed buildings) and factories are already over-loaded with routed wires and cables. Compared to installing new cables just for remote data acquisition, the prospect of sending measurements down existing network cables is very appealing.
Earlier this year, Pico Technology announced Internet Protocol (IP) networking support for its EnviroMon and PicoLog software products. The former runs on standalone data loggers and the latter is software for PCs fulfilling data–logging roles. Upgrading these products to support IP networking was relatively simple — although different approaches were required for the two products.
EnviroMon (software tailored for standalone applications) was revised to include a standalone program, called an agent, that passes messages received on an IP network to the logger hardware via a serial port. PicoLog, however, was revised to work under a ‘client–server’ scenario and the ‘remote instances’ of PicoLog appear on the ‘local instance’ as an IP device.
PicoLog (set up for short-term or intermittent data acquisition) and EnviroMon (which provides continuous, long–term data acquisition) both support Pico’s multitude of signal conditioners and sensors, making the measurement of virtually any parameter possible via an existing LAN, company network, or even over the Internet.
It is worth noting that remote access through IP is also appealing to those employing the Linux operating system (OS). With its built–in networking capabilities, and the fact that it requires no licence fee, Linux is growing in popularity within the design community and a significant number of Pico's clients are currently employing this OS. Linux is particularly well suited to remote data logging applications, where a Windows licence fee could easily add 20% to the cost of a basic system.
Pico provides Linux drivers for most of its products and so it is possible to develop a system with multiple remote sites running Linux, and then just one Windows interface at the central data collection point.
Safe as Houses
Security is of course an issue when considering data and the Internet. Many manufacturers are making remote measurements within a company or factory intranet environment, then sending the data (via a firewall) to a web server. External sites then have access to the data, but the internal network is protected against attacks. These customers are benefiting from shared data without laying new cables, and are able to present key data to the outside world.
Figure 2: The form factor of PC–based data acquisition products is proving popular with the majority of engineers: no longer is it necessary to grapple with bespoke hardware and software solutions (often prohibitively expensive for low-end applications).
On another note, much of today’s PC-based data logging technology will make its way from the factory environment and become the building blocks for homes of the future — homes that will be networked so that temperatures, humidity, light levels and even the amount of breakfast cereal left in the cupboards can be monitored. The recent extension of Internet addresses from 32 bits to 48, means that even the household fridge could have a web address and be accessible over the Internet.
On a more practical note, PC–based data logging could underpin major improvements in both household and commercial energy efficiency. For example, today’s central heating systems are currently limited by what the user can achieve with the three or four buttons on the controller. A computer could easily control household and office heating systems of the future, and a smart system could find the PC downloading weather forecasts from the web to manage the system in an efficient way.
PC-based data logging, IP networking and licence–free operating systems have broken down the cost versus complexity barriers that have, to date, barred progress in many environmental monitoring and data logging applications. In addition, the one thing that has got the industry to where it is today is its ability to measure and record progress, and employ technology that can acquire data from further and further afield.
Pico Technology would like to thank Test magazine for permission to re publish this article.
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