
Quadrus MINI Imager User’s Manual
A-25
Appendices
Appendix G — Interface Standards
Interface Standards, established by the Electronic Industries Association (EIA), specify
such things as the signaling voltage levels, maximum cable lengths, and number of drivers.
In the Quadrus MINI, selection of interface is made by pin assignment and, in the case of
host communications, by software switching between RS-232 and RS-422/RS-485.
RS-232
RS-232 defines an interface between two devices such as, for example, the reader and
host. It differs from the other interfaces by dedicating individual pins to specific functions
and by requiring both devices to share a common ground line. Since both device chassis
are connected to a common ground, a ground loop potential and the possibility of noise
interference exists. Therefore cable lengths are limited to a maximum of 50 feet (19.7m).
Despite being the most limited, this interface is used frequently because of the large
installed base of RS-232 equipment.
RS-422/RS-485
RS-422, unlike RS-232, measures signals deferentially; that is, the receiver looks at the
potentials between the two receive (or transmit) wires rather than the potential between
signal and ground. As a result, cables, if shielded, can be up to 4000 feet (1219m) in
length. Like RS-232, RS-422 communication is designed for only two devices on a single
line and must have a common ground. It can be used wherever RS-232 is used.
USB
The Universal Serial Bus can connect up to 127 devices to a host at a maximum of 6
megabytes per second (Mbps) of bandwidth.
Содержание Quadrus MINI
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Страница 12: ...xii Quadrus MINI Imager User s Manual Statement of RoHS Compliance...
Страница 98: ...4 20 Quadrus MINI Imager User s Manual Additional Notes about Calibration...
Страница 128: ...5 30 Quadrus MINI Imager User s Manual Setting Up the Imager for EZ Trax...
Страница 180: ...6 52 Quadrus MINI Imager User s Manual Background Color...
Страница 238: ...7 58 Quadrus MINI Imager User s Manual Configuring EZ Trax Output...
Страница 298: ...10 32 Quadrus MINI Imager User s Manual Skew Correction...
Страница 318: ...11 20 Quadrus MINI Imager User s Manual Request All Configuration Database Settings...
Страница 348: ...13 24 Quadrus MINI Imager User s Manual Other Operational Serial Commands...
Страница 362: ...14 14 Quadrus MINI Imager User s Manual Ordered Output Filter...
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