Glossary - 7
Percent Decode. The average probability that a single scan of a bar code would result in a successful decode. In a
well-designed bar code scanning system, that probability should approach near 100%.
PING. (Packet Internet Groper) An Internet utility used to determine whether a particular IP address is online. It is used to
test and debug a network by sending out a packet and waiting for a response.
Presentation Mode. Typically used when the digital scanner sits on a countertop or is mounted on a wall, in this mode, the
digital scanner operates in continuous (constant-on) mode, where it automatically decodes a bar code presented in its
field of view.
Print Contrast Signal (PCS). Measurement of the contrast (brightness difference) between the bars and spaces of a
symbol. A minimum PCS value is needed for a bar code symbol to be scannable. PCS = (RL - RD) / RL, where RL is
the reflectance factor of the background and RD the reflectance factor of the dark bars.
Programming Mode. The state in which a scanner is configured for parameter values. See Scanning Mode.
Quiet Zone. A clear space, containing no dark marks, which precedes the start character of a bar code symbol and follows
the stop character.
QWERTY. A standard keyboard commonly used on North American and some European PC keyboards. “QWERTY” refers
to the arrangement of keys on the left side of the third row of keys.
RAM. Random Access Memory. Data in RAM can be accessed in random order, and quickly written and read.
Reflectance. Amount of light returned from an illuminated surface.
Resolution. The narrowest element dimension which is distinguished by a particular reading device or printed with a
particular device or method.
RF. Radio Frequency.
ROM. Read-Only Memory. Data stored in ROM cannot be changed or removed.
Router. A device that connects networks and supports the required protocols for packet filtering. Routers are typically used
to extend the range of cabling and to organize the topology of a network into subnets. See Subnet.
RS-232. An Electronic Industries Association (EIA) standard that defines the connector, connector pins, and signals used to
transfer data serially from one device to another.