3-7 USB Extension Connection
Performance Considerations
3-4
PN: 10410-00783 Rev. A
MN25131A OM
3-7
USB Extension Connection
Two MN25131As are connected via fiber optic cables to allow USB operation over a long distance (farther than
the 5-meter limit for USB 2.0 wired connections). The fiber extenders in each unit are used to drive a fiber optic
cable pair that emulates a USB bus interface. One unit uses the USB-A to Fiber Extender to interface with one
of the two USB-B to Fiber Extenders on the second MN25131A.
One typical configuration, shown in
, is:
1.
A driving PC connects to the USB-B HUB input on the rear panel of the one MN25131A.
2.
A USB cable is connected from one of the USB-A connectors on the front panel and goes to the USB-B
connector of one of the two USB B to Fiber Extenders on the rear panel.
3.
The fiber cable is then connected into the Fiber Extender with the USB-A connector on the rear panel of
the second MN25131A.
4.
The output of the USB-A connector on the Fiber Extender with the USB-A connection is then cabled to
the USB-B HUB input on the rear panel. This then enables the front panel USB Hub to function as an
extension of the driving PC.
3-8
USB to SFP Optical Fiber Converters
The USB to Fiber converters are used to drive the fiber cable that extends the USB communications between
MN25131A extenders used in long-distance ME7868A installations. They consist of either USB-A or USB-B
2.0 connectors which are converted to LC Duplex drivers. The USB 2.0 connections drive a proprietary USB 2.0
to Bi-directional Fiber Optic SFP (small form-factor pluggable) converter. The type A USB 3.0 connector is
plugged into the Hub USB 3.0 type B connector with a short 1.5 foot patch cable. Only USB 2.0 signals are
passed, so the HUB drops down to High Speed USB 2.0 operation. This completes the path from the Host
computer to the Remote MN25131A Multi-function Extender via Full Duplex fiber optic cable with support for
lengths in excess of 100 meters. The Type A connector at the remote device side su5 V @ 1 A for the
converter. Power is disabled if no optical receive signal is detected. This has the benefit of disabling all USB
HUB activity if the fiber connection is broken, allowing shut down of the Remote Extender by simply
disconnecting the fiber optic connection at the Host side. When no optical power is detected, a low-duty-cycle
power up of the SFP+ Transceiver tests for optical power on the receiver. If power is detected, full power is
applied. Testing for optical power occurs every 10 Seconds and consumes very little battery power. Removal of
the SFP in the fiber extender with the Type A USB connection disables the testing for long term non-operation.
Figure 3-3.
MN25131A Fiber Extension Connections
From User PC
USB A to USB B from front panel HUB