This feature article was based on a survey (April 2003) conducted amongst users of data logging equipment and software in North America. To see how the trends correlated with what is happening in South Africa it was originally intended to interview several players in the local market. Time and other pressures saw only one guru being interviewed, this being Michael Hutton, the manager of National Instruments in South Africa. His views were complemented by information from the websites of the many other suppliers including Electronic Product Design, Osiris, ProMicro, Westplex and Spescom MeasureGraph.
One of the more interesting aspects where South Africa differs from the results contained in the survey is that whereas for use with systems having plug-in analog I/O boards the survey found that LabVIEW was the most popular followed by C++ and then Visual Basic. This is true in South Africa where LabVIEW is identified as by far the most popular programming tool but the US survey also indicated that for use with external chassis and module systems the order was C++, Visual Basic and then LabVIEW. Hutton believes that here LabVIEW still has the dominant share of the local market. The survey does however see the largest increase in usage share being expected for LabVIEW with it being the most popular by 2007; South Africa is already there. The survey does not mention GENIE-3, which is offered by local company ProMicro, or SoftWIRE, VEE or MATLAB, which is offered by Measurement Computing in the US, represented in South Africa by Osiris. The Keithley products offered by Spescom MeasureGraph also offer MATLAB in addition to LabVIEW.
Referring to connectivity the survey identifies RS232 as the leading protocol at present but sees USB as being the preferred connection by 2007 with Ethernet being second and RS232 and RS485 becoming less popular and GPIB disappearing altogether. The view of National Instruments is that RS232 and GPIB will still be with us well into the future as their use is just so extensive that many companies will be hesitant about making a change. What the survey does not address in detail is the current increase in use of FireWire (with which most laptops are today compatible) and the growing interest in wireless RF systems. USB is offered by both Measurement Computing and Ampro (represented locally by Electronic Product Design) while the latter company also offers high speed Fire Wire (IEEE 1394). They indicate that Fire Wire is often used with compatible cameras including high-speed devices where there is a requirement for downloading vast amounts of data.
When it comes to sampling rates the survey identifies an almost 50:50 split between under 10 000 and over 10 000 samples per second. Hutton pointed out that most cards today could sample at rates of 200 000 per second and these are in common usage even though their use in applications such as temperature or pressure measuring this capability is not required. For electronic measurements and vibration 500 000 sample per second could be required while there are high-end users out there who require up to 10 million samples per second. Measurement Computing (represented locally by Osiris) offers boards that typically offer 200 000 samples per second although one of their standard 12-bit boards has a 1,25 MHz sampling rate.
Resolution is another important factor although many users incorrectly equate resolution with accuracy. Here 16-bit is becoming the de facto industry standard. While there still are many users of 12-bit technology the higher cost of keeping to this resolution will see migration to 16-bit. Some users, depending on application, such as vibration measurement may opt for higher 24-bit resolution. On the question of resolution and accuracy there is not much sense in using a board capable of measuring -10 to +10 V if the measurement is just of a 0 to 1 V nature. Here if you really want accuracy you need to use a flexible card, which is programmable, to have different dynamic ranges which you can tailor to need. Looking at Measurements Computing the majority of their boards are 16-bit but they still offer a range of 12-bit boards at more competitive pricing than their wider 16-bit range.
After resolution comes the number of channels required and here the majority of users indicate 1 to 10 which Hutton agrees is the norm for South Africa. The survey showed that a smaller percentage of users (16%) required over 100 channels.
In terms of connectivity the survey indicates that the use of wireless networks is small and Hutton confirmed that while they have had a lot of enquiries about RF solutions, it just has not taken off and installations here still use cable. The future will however lie in the use of wireless technologies with Bluetooth and 802.11b leading the way.
In terms of the operating system on the PC this is virtually standardised on Microsoft Windows with use of Linux or other alternatives being virtually non-existent. Windows 98 and 2000 are currently the most popular but the number of users using XP is on the rise. The American survey believes that by 2007 the next-generation Microsoft operating system will be the most popular. Hutton confirmed this was the status quo in South Africa emphasising that the stability of the Microsoft products is getting better and better, and the ease of use and the fact that everything is there is why Windows has become virtually the only contender. It is interesting for potential Linux users to note that Westplex, the local distributor for Addi-Data, does offer Linux drivers.
One trend not identified in the survey but raised by Hutton is that many people now require their data on the move and are switching to PDA devices like the Palmtop where PCMCIA cards can be used as well and connectivity is ensured either by wire or an infrared link. LabVIEW can be run on a PDA device, PDAs today having up to 1 GB of memory. The data recorded on the PDA can always be downloaded to a PC for further detailed analysis if required. Software packages such as LabVIEW will also run on a PDA.
Today's PCs are defined around their use in office automation, which is of course the largest market. They were not designed with data logging in view and the number of free card slots also remains a problem. To adapt the PC for data logging, plug in I/O boards were developed along with bus architecture. These included Compact PCI, ISA, PC/104, PCI, PCMCIA (PC cards), PXI (an adaptation of Compact PCI), VME and VXI. According to the US survey the largest share of respondents were using PCI, PCMCIA and ISA boards with the least using PXI, VME and VXI. Over time it is expected that there will be significant growth in the use of Compact PCI and PXI boards with a reduced share of the market for the others. The Compact PCI was an adaptation of the PCI specification for rugged and embedded applications. PXI (originally developed by National Instruments but now an open industry standard) simplifies integration and increases the degree of compatibility between system controllers and the chassis of the different vendors.
In terms of selecting the product, the drivers were not based on price, accuracy being the dominant factor with ease of use and the number of channels being high on the list. When the rand was at its lowest to the $ then locally price may have had a strong influence. Hutton stressed that customers who made a selection based only on price often burned their fingers. In his opinion technical support and backup are also very important in the South Africa context.
Finally, when it comes to information sources about products and vendors, the survey found that the Internet rates very high up on the scale. Certainly having browsed the Web pages of many local suppliers the sites are full of valuable technical and price information. The majority of the websites of the local distributors link automatically to the manufacturer's home pages, and several of these pages allow browsers to directly compare performance and price with other vendors' products.
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Dr Maurice McDowell has many years' experience as a technical journalist, editor, business manager and research scientist. His third party analyses of world-class companies and processes, as well as his insight into industry and technology trends are well respected.
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