Moog Components Group
4 Port 10/100/1000 Mbps Ethernet Switch
February 23, 2009
(201640-xxx)
Page 12 of 13
To determine if the fiber is broken, a laser module is out, or the board is malfunctioning, first:
•
Verify that the optical transceiver is tight in its socket.
•
Check all fiber optic connections including WDMs and slip rings to make sure that they are not
causing the problem.
•
Check that the optical fiber cable is straight at connectors on board for minimum optic loss.
1.8
DIAGNOSTIC OVERVIEW
The Fiber Optic Modem Board has been re-designed to include hardware and firmware for monitoring
various parameters of interest. This capability is accessed via a 2 pin Phoenix connector on the front
panel that carries bi-directional RS-485 telemetry to the modem. The diagnostics modem will typically
be used in conjunction with a user-supplied PC on the surface, which has been loaded with PRIZM
Modem Monitoring S/W.
The initial release of the Diagnostics feature required that the user allow for the use of one RS-485
channel in the multiplexer system for connectivity between the topside Diagnostic PC and the remote
multiplexer. Later releases are capable of carrying the Diagnostics across the fiber link via a high-speed
data bit on the back plane.
NOTE: The diagnostics feature in no way interferes with normal operation of the modem – it is
not necessary to be running the diagnostics s/w for the modem to work.
1.9
Communications Hardware
The diagnostics capability is accessed via the 2-pin RT+/RT- connector on the front panel of the modem,
which provides the RS-485 connectivity to the on-board processor for diagnostics communications. The
initial release of the Diagnostics feature required that the user allow for the use of one RS-485 channel in
the multiplexer system for connectivity between the topside Diagnostic PC and the remote multiplexer.
RS-485 was used because of its multi-drop capability, which in this case allows all the modems to be
communicated with via a single channel. In later revisions of the diagnostic modems, the ability to carry
the diagnostic data across the fiber link using one of the high-speed back plane bits was included. In this
configuration, no RS-485 multiplexer channel is needed, however one of the high-speed data bits is
sacrificed.
NOTE: A modem configured to operate over the back plane will NOT operate correctly if
used with a modem that is configured to operate over a RS-485 multiplexer channel.
The user is required to communicate with the modems of the system via RS-485. A typical installations
is shown in the following drawing. This details a diagnostic connection through a RS-485 submux
channel.
