Using CompactFlash in industrial PCs

Industrial Computer Hardware

Computer and peripheral suppliers

I/O sensor/computer interfacing suppliers

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April 2006 Industrial Computer Hardware

Information from Centurion Micro Electronics

Most industrial PCs or single board computers (SBC) are fitted with CompactFlash sockets. This allows the system to boot and run from a CompactFlash instead of a hard disk drive. CompactFlashes are physically smaller and can handle shock and vibration much better than hard disk drives. They have simulated heads, sectors and cylinders just like normal hard disk drives, allowing the PC BIOS to treat them like a normal hard disk drive.

CompactFlash are also used in digital cameras. The high volume created by the demand from these and other consumer products have resulted in much lower pricing. Supplier competition has pushed pricing down further. All of this has been good for the Industrial PC field. Lately however, the consumer market has required higher capacity and speed from the CompactFlash suppliers. This is needed to take more high resolution pictures at faster rates than before. Suppliers have responded by switching to a technology called MLC (multilevel control). This means each flash cell can have four different voltages, allowing them to store two digital bits in one flash cell. This doubles the capacity and increases the speed.

The data reliability however, is now lower. If one bit is read incorrectly, the shade of one of the colours of one pixel in a picture may be slightly wrong. Normally this is difficult to detect by an untrained eye. However, an incorrect bit in a PC's hard drive can easily cause the system to crash.

For this reason Centurion Micro Electronics (CME) supplies CompactFlash cards based on binary (not MLC) technology. Every cell only stores one digital bit using two voltage levels only. This type of CompactFlash is often referred to as industrial grade. They are also optionally-available in extended temperature ratings.

Sandisk used to supply industrial grade CompactFlash. Early this year, Sandisk stopped the production of these industrial grade items. Its Ultra Grade CompactFlash is however, also reasonably reliable and operate in most of the industrial PC applications. Simpletech has continued producing industrial grade CompactFlash based on binary technology. Both types are available from CME.

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Industrial Computer Hardware

Using CompactFlash in industrial PCs

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