Electronics and Mechanical Components - Microscan - #4

T. he routing of connectivity cables should be carefully designed to minimize the risk of damage.

Scanning Considerations. Designers value compact components, and bar code readers are no exception. How­ever, more important than the size of the reader is the space available for reading. Designers need to calculate the scan envelope before specifying a bar code reader. Smaller scan envelopes offer the design advantage of requiring less physical space between the reader and the bar code.

For someone assessing readers' specifications compara­tively, the speed parameter can be misleading. A scanner's decode rate often is more important than the more com­monly cited read rate for embedded applications, because it determines how fast the scanner will be able to process the encoded data and send it to the host.

Interface Considerations. Triggers that tell the scan­ner when to look for the bar code arc divided into two categories: discrete (external) and serial (software). Which type to include generally depends on the designer's preference for programming or wiring. Discrete triggers are separate sensors, or object detectors, that can be wired directly into the reader. They typicallv require much less programming than serial triggers. Serial triggers arc dis­patched from an external device, such as a programmable logic controller or host personal computer, that tells the reader to look for a bar code. Serial triggers are often used

in embedded applications to provide greater control.

Once the bar code is decoded, the reader can output the data in the particular format required for a specific process. Interface software should be designed to initial­ize the reader, check for status, and create a robust real­time communication protocol between reader and host.

Bar codes have proven their value for ensuring the accuracy of medical information and protecting patient safety. The value of bar code reader components for IVD manufacturers is changing because of recent technology advances. Now is a good time for instrumentation manu­facturers to reexamine available bar code component technology in order to sec whether these advances can provide performance or total-cost-of-ownership advan­tages in embedded designs. The use of bar codes in labo­ratories and hospitals continues to increase, so I VD equipment must evolve to meet growing needs. —Niels Wartenberg, Microscan Systems (Ronton, WA)

More information about the products and services of companies in this section is posted on the IVD TechnologyVJeb site at: medical I I, www.ivdtechnoiogy.com. device L.I 11\

ivdtecnnology.com IVD TECHNOLOGY | OCTOBER 2007 79

MICROSCAN