Lantronix
ION219-x Install Guide
33412 Rev. D
32
USB (Universal Serial Bus)
USB uses 4 shielded wires:
•
two for power (+5v and GND)
•
two for differential data signals (labelled as D+ and D- in pinout)
NRZI (Non Return to Zero Invert) encoding scheme used to send data with a sync field to synchronize the host
and receiver clocks. In USB data cable, Data+ and Data- signals are transmitted on a twisted pair—no
termination needed. Half-duplex differential signaling helps to combat the effects of electromagnetic noise on
longer lines: D+ and D- operate together; they are not separate simplex connections. See Figure 29 below.
Table 2: USB Pinouts
Pin
Name
Cable Color
Description
1
VCC
Red
+5 VDC
2
D-
White
Data -
3
D+
Green
Data +
4
GND
Black
Ground
Figure 14: USB Peripheral and Cable Ends
Cable Shield Grounding
Media converter network cabling can be shielded or unshielded. Shielded cables must be grounded, according to
the specific requirements of the media and port type. For example:
•
Shielded RJ-45 cable used for 100Base-Tx Ethernet MUST be grounded at both cable endpoints via
shielded RJ-45 jacks.
•
Shielded RS-232 cable MUST have the shield grounded at both cable endpoints via shielded RS-232
connectors.
•
COAX cable used for 10Base-2 Ethernet MUST only be grounded at a single point.
Some media converters provide a jumper option or other grounding mechanism. Special attention should be given
to the grounding requirements of coaxial cable circuits. Installation may require grounding at both cable ends or
only one cable end or neither cable end. See the individual device user guide for grounding requirements.
