Transcript Termination Boards

Termination Boards
Dynamic Positioning Cabinet
Termination Boards Overview
The termination Boards provides the
connections between the field and the
Process Bus.
 For each signal the TB also provides a
fuse for the overvoltage protection.
 Each type of signal need a specific type
of TB.

Types of Termination Boards

There are four types of TB:
TB DI ISO
 TB AI
 TB AIO DIF
 TBSS

TB DI ISO
The TB DI ISO is the termination boards
for the digital signals.
 The current loop can be powered from
the card, or from an external power
supply.
 The powering method is specific for each
channel and can be configured from this
board.

TB AI

TB AI channels are normally powered
from external power supplies.

The internal loop power connections
includes a transient voltage suppressor
to protect all channels on the board from
overvoltage due to excessive voltage
from the power supply.
TB AI - Short circuit protection

If an internally powered loop is short
circuited, the fuses in the power lines on
the termination board are blown.
Consequently, all channels on that board
fail. However, the power supply itself and
the channels on other termination boards
which are supplied from the same source
are not affected.
TB VOTING
The TB VOTING card comprises two processing
stages for each of six analogue output
channels.
The first stage checks validity of the signal
sources. If any of the sources A to C are not
valid, the stage logic duplicates signals from
one valid source to replace the not valid ones.
This is done to ensure the best inputs for the
second processing stage.
TB VOTING
The second stage selects the median
value from three inputs “A” to “C” for
each individual output channel. The
median value is the one having
momentary value between the two
others on the voltage scale. The voting
comparators provide hysteresis to
ensure signal stability for each output
channel.
TB AIO DIF & TB AO V&C
The TB AIO DIF card provide the
necessary amplification for the output
signals.
 If the failsafe alarm is active for some
reason the card provide the appropriate
“zero” signal to the thrusters.
 For each thruster the failsafe signal is
configured on the AO V&C card.

TBSS
The Termination Board Serial Switch
(TBSS) is designed for switching serial
lines to field equipment in a doubleredundant computer system.
It provides connectors for four serial lines
from each of two Single Board
Computers (SBCs) and connectors for
four serial lines to field equipment.