Technical Manual
48
The telemetry system gives a transparent, full duplex serial link between the
Subsea Microcontroller Board and the Topside PC capable of transferring data
at 19200 baud.
LED Indicators
Seven LED indicators are fitted to the Subsea Telemetry Board. Three green
LEDs show the power supply status: “+15V” and “-15V” are generated by the
Subsea Power Supply Board, while “+5V” is derived from the +15V supply by
an on-board voltage regulator. Four yellow LEDs monitor communications
activity: “Rx0” is illuminated whenever a character is received from the
Subsea Microcontroller Board; “Tx0” when a character is transmitted to the
Subsea Microcontroller Board; “Tx1” when a character is transmitted to the
Topside Telemetry Board; “Rx1” when a character is received from the Topside
Telemetry Board.
Automatic Tuning
The automatic telemetry tuning sequence takes approximately 5 seconds if
both telemetry boards are active and there are no hardware faults. During
tuning, the “Tx1” LED is illuminated, while the “Rx1” LED turns on and off at
about 1 second intervals. Once two-way communication has been established,
both “Tx1” and “Rx1” will blink very rapidly at about equal intensity, showing
that handshake messages are being transmitted and received.
Maintenance
NOTE:
Appropriate safe working practices should be followed to ensure
that all hazards are minimised.
When the system is in operation, the Electronics Pod should be washed down
with clean, salt-free water whenever it is returned to the deck of the vessel.
This will reduce corrosion, and enable thorough inspection of all the main
housing, connectors, and connecting cables.
Where the pod is disassembled, all the o-rings should be checked to ensure
that none of them are damaged. It is recommended during reassembly, to use
a small amount of silicone grease on the o-rings to prevent chafing.
It is good working practice to regularly check all fastenings to ensure they are
present, tight, and there is no damage to them or the items they are fitted to.
Any damaged fastenings should be replaced immediately.
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