CompactFlash Data Acquisition Frequently Asked Questions

The following are the most frequently asked questions about CompactFlash data acquisition.

What is CompactFlash (CF)?

CompactFlash is a very small form factor that can be used for data storage and I/O. A CompactFlash card has 50 pins and adheres to PCMCIA-ATA specifications. They provide identical functionality to PCMCIA cards but CF-Type II modules take up much less space. The CF-6004 measures a tiny 43mm (1.7") x 36mm (1.4") x 5mm (0.19") and weighs less than 1/3 of an ounce.

What are some common applications for CompactFlash data acquisition?

The CF-6004 is ideal for any application that can benefit from portable, handheld measurements. Common applications include, but are not limited to:

• Biomedical – wearable computing, physiological monitoring
• Automotive diagnostics – Automotive service centers
• Education – lab/experimental use
• Food – Handheld pH meter
• General data logging
• Machine monitoring – Vibration analysis
• Consolidation of multiple handheld instruments (i.e. DMM, scope, etc.)

With LabVIEW PDA as the development environment, CompactFlash applications also benefit from the flexibility of virtual instrumentation. A technician with a PDA, for example, can go to a factory test station and connect the CF-6004 to a set of temperature sensors to log temperature data. Using the same PDA, the technician can then go to a different test station with pressure transducers and record pressure data.
Most modern PDAs are equipped with built-in wireless connectivity. With LabVIEW PDA, it is possible to stream data to another computer in real time using TCP, IRDA, or Bluetooth.

What types of connectivity options are available for CompactFlash DAQ?

As shown by Figure 3, there are several options for connectivity to the CF-6004. The NI SCB-15 is a shielded terminal block which is compact and ideal for applications where size is a concern. Another terminal block is the NI CB-15, which is a standard size that can be mounted on a DIN rail. If your application requires custom connectivity, there is also the option of a cable with bare wires that you can use with the connector of your choice.

I have a limited battery capacity on my PDA and my application involves acquiring lots of data. How much power does the CompactFlash card require?

The CF-6004 is optimized to consume the minimum amount of power that is necessary. During continuous acquisition, it uses just 50 mA and in an idle state, it uses less than 2 mA. PDA batteries are currently available with capacities up to 3600 mAh. This means that you can continue to take measurements over a long period of time and still have the peace of mind of knowing your battery is up to the task.

What devices currently support CompactFlash technology?

More than 155 handheld PCs, Pocket PCs, and Tablet PCs currently leverage CompactFlash technology. These include products from popular manufacturers such as HP and Dell. For a complete list, visit the CompactFlash Association’s webpage. CompactFlash is a proven technology and will continue to be used in portable computing platforms for years to come.

What will I need in order to begin acquiring data with the CF-6004?

You will need:

• LabVIEW with PDA Module for PocketPC
• DAQmx Base driver version 1.0.1 (available as a free download from ni.com)
• Your choice of connector cable (and terminal block, if you so choose)
• PDA with a CompactFlash Type II slot running PocketPC 2003

With these things, you can quickly begin taking measurements using the CF-6004 and an off-the-shelf PDA.

For data acquisition, does a PDA offer any advantages over a laptop, other than size?

In addition to providing the flexibility of multiple measurement applications or unique measurement capabilities on a single PDA, virtual instrumentation for handheld devices also can provide cost savings over more traditional portable measurement solutions such as laptops. Table 1 shows the cost savings gained using the PDA platform for a sample portable monitoring system to be deployed in several service centers. By purchasing as few as 10 handheld systems, you can save about $6,400 over a desktop or laptop system. The following calculations are based on average laptop prices from Dell, average PDA prices from Palm and HP, average PCMCIA DAQ device prices from NI, CF-6004 price, and LabVIEW Full Development System, PDA module, and PDA deployment license prices.
Absolutely – the DAQmx Base VIs are capable of programming a variety of devices. You can develop and test your application in the comfort of your office on a desktop PC using another DAQ device such as the USB-9215. You can then deploy the exact same code to your PDA for use with the CF-6004. The flexibility of LabVIEW is what makes this transition possible.

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PDA's with Host USB
There are now PDA's on the market that support Host USB, including the Juniper Systems' Archer. It is now possible to control the USB-6008 and USB-6009 modules using the Archer device.
- Karl Nicholas, Juniper Systems Inc. karln@pacbell.net - Aug 7, 2007