Navitron NT777 MK2 User manual

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
NAVITRON SYSTEMS LTD
NT777 MK2 AUTOPILOT
INSTALLATION & OPERATION MANUAL
17 The Tanneries
Brockhampton Lane
Havant, Hants, U.K. PO9 1JB
Registered in England No. 2607869
Tel: [phone]
Int. Code: +44 23
Email: [email protected]
Web: www.navitron.co.uk
1123/2

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
- Contents -
1. Functional Description of Standard Units.
2. Standard Unit Dimensions and Installation.
3. Standard Unit Cables and Connections.
4. Installation Adjustments and Alongside Trials.
5. Application Notes (Including Proprietary
Remote Power Steer Connections).
6. Optional Equipment Installation.
7. Operator Controls and Sea Trials.
8. Display Messages, Alarms, Status Indicators and
Autopilot Diagnostic mode
9. Short Operating Instructions.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
General: -
All Navitron Autopilot systems are designed and developed by Navitron
Systems Ltd. to meet the rigorous and diverse demands of commercial
applications from coastal work boats through trawlers and off shore
support craft to ocean going gyro based vessels of several thousand gross
registered tonnes.
Accordingly the NT777 MK2 Autopilot System is equipped with full PID
intelligence, which enables it to monitor and respond to straightforward
control settings to provide optimum steering performance in all operating
conditions.
In addition to the PID intelligence inherent in the NT777 MK2 control
electronics, the potential diversity of steering systems types is also
accommodated by the inclusion of automatic and manual installation
adjustments which easily enable Autopilot demands to be matched to
individual steering system characteristics.
Designed to operate from a supply voltage of 11-40Vdc, the standard
NT777 MK2 Autopilot also contains Track steering Interface circuitry
rendering it suitable for direct connection to proprietary GPS receivers etc.
Four Track modes are provided:-
(i) Cross Track Error correction only (“XTE” mode) using NMEA
0183 Sentences APA, APB, RMB, XTE or N2K data.
(ii) Multi-waypoint steering featuring Cross Track Error correction
with automatic course change to next waypoint (“BER” mode)
using NMEA 0183 Sentences APB & RMB.
(iii) Remote course setting facility (“HTS” mode) via the NMEA
0183 APB, HSC or HTC sentences.
(iv) Multi-waypoint steering featuring full control of Course Over the
Ground with Cross Track Error correction and automatic course
change to next waypoint (“COG” mode) using NMEA 0183
Sentences APB, RMB & RMC.
The standard NT777 MK2 series Autopilot configuration therefore requires
the availability of a good quality externally gymballed magnetic card
compass and/or NMEA 0183 Heading Data available from a proprietary
electronic compass or GPS Gyro etc, electrically operated (11-40Vdc/5A
max) solenoid valves for steering system control and –if the Track Steer
function is to be utilised –NMEA 0183 track data from a suitable GPS
receiver or Track Plotter.
NB: Whilst all efforts have been made to ensure the safety and
reliability of the NT777 MK2 Autopilot range, it should be noted that
the installation of any such system, should never be permitted to
detract from the adequate provision of sound and continuous
watchkeeping duties.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Typical NT777 MK2 Autopilot Installation

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Autopilot System Input / Output Specifications
Main Supply Voltage Range
18 –40Vdc
Single / Backup Supply
Voltage Range
11–40Vdc
Power Consumption
10W
Illumination Max
2W
Mag Heading Input Port
Navitron
HSC etc.
Coil Type
HSC 1 or HSC 2
Resolution
0.25º
Inputs:-
NMEA 0183 Heading Input Port
Channel 1 / 2
Mag
Gyro
NMEA 0183 /
IEC61162-1 or -2
(Gyro /Mag and
4800 / 38400 baud
Selectable)
$XXHDM
$XXTHS
$XXHDG
$XXHDT
$XXHCC
$XXHDM
$XXTHS
$XXHDG
$XXHDT
$XXHCC
$XXROT
$XXROT
Heading Input Resolution 0.1°
N2K Input Port (PGNs Accepted)
ISO Request
059904
Heading / Track Control
127237
Vessel Heading
127250
Rate of Turn
127251
Magnetic Variation
127258
COG & SOG Rapid Update
129026
Cross Track Error
129283
Navigation Data
129284
Direction Data (COG & SOG)
130577
Load Equivalency Number (LEN)
1
Track Steer Data Input Port
NMEA 0183
IEC 61162-1 or -2
Track Data from GPS /
Track Plotter
$XX APB, $XXRMB,
$XXXTE, $XXHTC
$XXHSC, $XXAPA,
$XXRMC
Op. Temp. Range
-20 to +60 ºC
Compass Safe Distance
Control Unit
0.5m
Distribution Unit
0.5m
Mechanical Data
Control Unit
Distribution
Unit
Width
192mm
240mm
Height
120mm
310mm
Depth –(behind
bezel for Control
Unit)
80mm
75mm
IEC 60945
Equipment
Category
Protected
Protected
NMEA 0183 / IEC 61162-1 or -2 Heading / Rudder Position
Data Output Port (Isolated RS422)
Update
Rate
Selectable at
1Hz, 10Hz, 20Hz or 40Hz
(>10Hz at 38K4 baud only)
Hz
Mag
Heading
True
Heading
ROT
Rudder
Position
1
$AGHDG
$AGHDT
$AGTHS
$AGROT
$AGRSA
10
$AGHDG
$AGHDT
or
$AGTHS
$AGROT
(5Hz)
$AGRSA
(5Hz)
20
$AGHDG
$AGHDT
$AGTHS
$AGROT
(10Hz)
$AGRSA
40
$AGHDG
$AGHDT
or
$AGTHS
$AGROT
(10Hz)
$AGRSA
(20Hz)
Outputs:-
Solid State Solenoid Switching (Rudder Control)
Polarity
Common +VE / -VE Selectable
Max Rating
5A @ 11-40Vdc Max
System Alarms
Main Power Fail
Watch Alarm Timeout
Back Up Power Fail
OHA Limit
Heading Data Fail
Control Unit Fail
Track Data Fail
Course Change
Steering Fail
Track Heading Change
Distribution Unit Fail
Remote Control Engaged
Limit Switch Status
Rudder Ref Unit Fail
Alarm Contacts are available (rated 3A) for Watch Alarm and
Power / General Failure.
N2K Output PGNs
ISO Acknowledgement
059392
ISO Request
059904
ISO Address Claim
060928
PGN List
126464
Product Information
126996
Rudder
127245
Vessel Heading
127250

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Section 1: Standard Units Supplied.
1.1 The NT777 MK2 Control Unit.
1.2 The NT777 MK2 Distribution Unit.
1.3 The Heading Sensor Coil.
1.4 The Compass Junction Box.
1.5 The Rudder Reference Unit.
1.1 NT777 MK2 Control Unit (FIG 1.1).
The control unit is the principal element from the viewpoint of the operator
and contains the electronics associated with the display drive circuitry and
all operator control communications with the distribution unit.
The Control Unit also supplies a variable illumination output for optional
instrumentation which might be mounted in the immediate vicinity.
For further Control Unit information refer as follows: -
Installation
Section 2.1
Connection
Section 3.1
Preset Adjustments
Section 4 and 7
Operator Controls
Section 7 and 9

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
1.2 NT777 MK2 Distribution Unit.
This unit is the central distribution point of the NT777 MK2 Autopilot
system since, in addition to all of the electronic control intelligence and
associated voltage regulation etc. it houses the solenoid switching stages,
both aspects of which are internally fuse protected at 2A and 5A
respectively.
FIG 1.2.1 Simplified NT777 MK2 System Block Functions.
The voltage regulator stage is immediately and automatically compatible
with ships’ power supply of 11–40Vdc (single supply) or 18-40Vdc (dual
supplies) whilst the solid-state switches responsible for the excitation of
the ships solenoids are suitable for 11-40Vdc and rated 5A maximum.
Note: Where solenoid voltages outside of the standard range (11-
40Vdc) are applicable, a separate optional relay box must be
employed (i.e. 110/220V ac/dc etc).

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
FIG 1.2.2 NT777 MK2 Distribution Unit.
For further Distribution Unit information refer as follows: -
Installation
Section 2.2
Connection
Section 3.1

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
1.3 The Heading Sensor Coil Type HSC2 (FIG 1.3).
This unit contains two main sets of windings which, when installed above
or below and in close proximity to the proprietary steering compass
produces (in conjunction with the magnetic flux of the steering compass)
an electronic heading reference.
The Heading Sensor reference signal is initiated by a Distribution Unit
generated 400Hz wavetrain applied to the sensor coil excitation winding.
The resultant waveforms induced into the heading sensor star windings
are resolved by the digital electronics within the distribution unit.
A total of 6 electrical connections are required between the Heading
Sensor Coil (type HSC2) and the distribution unit and these are routed via
a two entry Compass Junction Box supplied.
FIG 1.3 Simplified Heading Sensor Coil (type HSC2) Schematic.
For further Heading Sensor information refer as follows: -
Installation
Section 2.3
Connection
Section 3.2
1.4 Two Entry Compass Junction Box.
This unit has no electronic component content housing only a terminal
block to facilitate electrical connection between the Distribution Unit and
Heading Sensor Coil.
For further Compass Junction Box information refer as follows: -
Installation
Section 2.4
Connection
Section 3.2
Distribution
Unit

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
1.5 The Rudder Reference Unit (FIG 1.5).
This unit incorporates a conductive plastic potentiometer and two limit
switches (Port and Starboard) with associated cams.
The potentiometer continuously signals the precise angular position and
velocity of the rudder to the control unit whilst the limit switches are
adjusted and set during installation to ensure that the rudder is not driven
unnecessarily to its mechanical extremes.
The potentiometer end voltage is factory calibrated to 7.0Vdc within the
distribution unit and the limit switches are configured to break the low
current drives associated with the port and starboard solid-state switch
stages.
Note: Electronic Limit Switches are also a standard feature of the
NT777 MK2 Autopilot
FIG 1.5 Simplified Rudder Reference Unit Schematic.
For further information refer as follows: -
Installation
Section 2.5
Connection
Section 3.3
Alongside Trials
& Adjustments
Section 4.1
Mechanical Switches
Section 4.1
Electronic Switches
Sections 4.14 –4.16
Distribution Unit
Solid
-
state
Switches
Control
Electronics
Port Limit
Stbd Limit
Feedback Potentiometer

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Section 2: Standard Unit Installation.
2.1 The NT777 MK2 Control Unit.
2.2 The NT777 MK2 Distribution Unit.
2.3 The Heading Sensor Coil (Type HSC2).
2.4 The Compass Junction Box.
2.5 The Rudder Reference Unit.
Installation Note –Radio Frequency Interference (RFI).
All Navitron Autopilot systems exhibit high levels of RFI rejection (MF, HF
& VHF) by virtue of careful decoupling and suppression measures
exercised as a standard Navitron Systems design function and are
compliant with the statutory requirements of EN60945 (IEC60945).
However, any potential risk of cross coupling should be minimised where
possible by ensuring that Autopilot components and associated cable
routing is afforded the greatest separation possible from high power
transmitters, couplers and other RF carrying cables.
2.1 NT777 MK2 Control Unit Installation (FIG 2.1).
Compass Safe Distance –0.4m.
The Control Unit is suitable for external location and should be installed
close to the main steering position and commensurate with clear field of
operator vision.
The unit may be panel or foot mounted as required (mounting bracket
provided) with allowance made for cable access to the cable entry glands
at the rear of the unit.
Outline dimensions and mounting details are shown in FIG 2.1.
Note. Where the cut out detail shown in FIG 2.1 is not possible to observe
due to DIN cut outs (no corner fixing screws possible) a U bracket
mounting kit is provided.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
FIG 2.1 NT777 MK2 Control Unit Outline
Dimensions & Mounting Details.
2.2 The NT777 MK2 Distribution Unit Installation.
Compass Safe Distance 0.4m.
The distribution unit is not suitable for external location and must be
installed in an enclosed wheelhouse location.
Four fixing positions are exposed when the lid is removed.
Outline dimensions are shown in Fig 2.2.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Fig 2.2 NT777 MK2 Distribution Unit Outline Dimensions.
2.3 The Heading Sensor Coil type HSC2.
Navitron Heading Sensor Coil type HSC2 contains encapsulated electronic
components requiring 6 connections and is factory fitted with a 1.5 metre
length of 6-core cable accordingly.
The Heading Sensor Coil (HSC2) should be mounted above or below a
reasonable quality externally gymballed magnetic compass such that it can
interact with the massive magnets normally associated with a compass of
this type.
NB: INTERNALLY GYMBALLED COMPASSES ARE NOT SUITABLE
FOR HEADING SENSOR COIL MOUNTING.
The HSC2 should be centrally located above or below the pivot point of the
compass card as accurately as possible. Any eccentricity will introduce
errors.
A mounting bracket in non-magnetic material should be employed and the
HSC2 should be mounted to this with the cable entry as shown in FIG 2.3.
Typically, the HSC2 may be mounted close to the glass or the base (as
appropriate) of the compass. However, the distance between the HSC2
and the compass magnet will affect the signal strength from the sensor.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
SYNCHRO CLAMPS
EQUALLY SPACED
ON 85.5mm PCD
MOUNTING SLOTS
72mm CENTRES
CENTRE MOUNTING HOLE
HOLE 8mm DIA
(USE NON-MAGNETIC
STUD OR BOLT)
CABLE
ENTRY
15
79mm
65mm
68mm
20
FORE
2.5mm
45o
30o
45o
110
80
32
60
30
2.3 The Heading Sensor Coil type HSC2 (Continued).
Later calibration may determine that a non-magnetic spacer must be
introduced between the HSC2 and its mounting bracket to increase the
distance between the HSC2 and the compass magnet.
FIG 2.3 HSC2 Mounting Details.
2.4 Compass Junction Box Installation (FIG 2.4).
The junction box should be located and secured in the vicinity of the
magnetic compass and within the scope of the 1.5 metre cable length fitted
to the heading sensor coil. Whilst the box is splash proof it should be
mounted in an accessible but sheltered position.
Two screw fixing holes are provided in the base of the box and are
exposed when the lid is removed.
All dimensions in mm
FIG 2.4 Compass Junction Box Outline Dimensions.
(Connection details are shown in section 3.2)

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
2.5 Rudder Reference Unit Installation (FIG 2.5).
The Rudder Reference Unit should be located and secured in the steering
compartment, or tiller flat, such that the Reference Unit arm (X) may be
mechanically coupled to the Rudder arm (Y) to provide a linear angular
relationship between Rudder arm and Reference Unit arm movements
(see Figure 2.5.1).
FIG 2.5 Rudder Reference Unit Outline Dimensions.
FIG 2.5.1 Rudder Reference Unit Installation.
X
RUDDER
STBD
PORT
AFT
B
A
Y
STBD



NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
2.5 Rudder Reference Unit Installation (Continued).
NOTE: The relative arm lengths of X and Y (the X: Y ratio) should be
nominally 1.5:1 and angles between arms X and Y and the
connecting rod should be 90° when the rudder is amidships.
When the rudder Reference Unit is finally bolted down, check the
following: -
(i) That the entire linkage configuration is backlash free and
unrestricted in its range of movement when the rudder is moved
from hard over Starboard to hard over Port and vice versa.
(ii) The direction of the Rudder Reference Unit arm when the rudder
moves to Starboard (i.e. Note direction A or B marked on the
Rudder Reference Unit).
Further information on the Rudder Reference Unit is contained in sections
3 & 4 as follows: -
3.3 Rudder Reference Unit Connections.
4.1 Limit Switch Adjustment.
4.3 Rudder Reference Unit phasing.
4.11 Rudder Bias (midships alignment).
4.12 Rudder Angle Calibration.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Section 3: Standard Unit Cables & Connections.
The ‘Standard Unit’ cables referred to in section 3 include provision for
GPS input for waypoint steering. However, it should be noted that the
Autopilot system will function without GPS or Track Control input if the
Track function is not required.
3.0: NT777 MK2 Interconnecting Cables.
3.1: NT777 MK2 Control Unit and Distribution Unit Connections.
3.2: HSC2 Sensor Coil Connection to Compass Junction Box.
3.3: Rudder Reference Unit Connection.
3.4: Port & Starboard Solenoid Connections & Suppression.
3.5: NMEA 0183 Input Connections from GPS/Plotter/Track
Control System.
3.6: Optional NMEA 0183 Heading Output Connections.
3.7: NMEA 0183 Heading Input Data from proprietary Electronic
Compass / GPS Gyro etc.
3.8: Optional N2K Connections.
3.9: Optional Watch Alarm Connections.
Note: Additional cables and connections associated with optional
equipment (Remote Power Steer Controls and Rudder Angle
Indicators etc.) are shown separately in Section 6.
3.0 Cable Routing.
When routing interconnecting cables, consideration should be given to the
remarks concerning Radio Frequency Interference (RFI) in section 2. For
this reason any potential risk of cross coupling should be minimised where
possible by ensuring that screened cables are employed throughout and
that cable routing is afforded the best separation possible from transmitter,
couplers and other RF associated cables.
Commensurate with the use of screened cables, earth points are fitted
within the NT777 MK2 Control & Distribution Units adjacent to the cable
entry glands to provide screen terminations for all cables entering.
In addition, an external 4mm dia earth stud is available on both units and
must be connected to the Ships earth via a flat braid or earth tape.
With the foregoing duly noted, all cables should be routed in accordance
with FIG. 3.0 as follows: -

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
FIG 3.0 NT777 MK2 Autopilot System Interconnection cables
NOTE: The NT777 MK2 DB accepts dual 24Vdc (18-40Vdc) electronics power supplies or a
single 12Vdc / 24Vdc (11-40Vdc) supply. See Section 3.1.1 for details.
Cable
No.
Cable Type
Cable Size
1
2 Core screened
1.0mm232/0.2mm
2
2 Core screened
1.0mm232/0.2mm
3
2 Core screened
1.0mm232/0.2mm
4
3 Core screened
1.0mm232/0.2mm
5*
2/3 Core screened
0.5mm216/0.2mm
6*
4 Core screened
0.5mm216/0.2mm
7*
2 Core screened
0.5mm216/0.2mm
8*
5 Core screened
0.5mm216/0.2mm
9*
4 Core twin twisted
pair screened
0.22mm27/0.2mm
10*
2 Core twin twisted
pair screened
0.22mm27/0.2mm
11*
2 Core twin twisted
pair screened
0.22mm27/0.2mm
Cable
No.
Cable Type
Cable Size
12*
2 Core twin twisted
pair screened
0.22mm27/0.2mm
13*
2 Core twin twisted
pair screened
0.22mm27/0.2mm
14
6 Core screened
0.5mm216/0.2mm
15
6 Core screened
0.5mm216/0.2mm
16*
2/3 Core screened
0.5mm216/0.2mm
17*
7 Core screened
0.5mm216/0.2mm
18*
7 Core screened
0.5mm216/0.2mm
19*
4 Core twin twisted
pair screened
0.22mm27/0.2mm
20
4 Core twin twisted
pair screened
0.22mm27/0.2mm

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
Fig 3.1 NT777 MK2 System Connection details.

NT777 MK2 AUTOPILOT INSTALLATION & CALIBRATION
3.1 NT777 MK2 Control & Distribution Unit Connections.
Twenty cable gland entries are located on three faces of the Distribution
Unit and two cable gland entries are located at the rear of the Control Unit
case.
The terminal connectors within the NT777 MK2 Control Unit are accessed
by removal of 6 x M3 slotted screws, which are located on the Control Unit
rear gland plate assembly.
Note: If fitted the gland plate mounted buzzer is connected to the internal
PCB via a flying lead and polarised plug. Disconnect to remove the
gland plate. Ensure the plug is reconnected when refitting gland
plate (see FIG 3.1A)
FIG 3.1A Buzzer Connections.
The terminal connectors within the NT777 MK2 Distribution Unit are
accessed by removing the six lid retaining screws.
The terminals are plug and socket types, which can be separated to permit
simple screw terminal connection of cable prior to reinsertion.
1 2 3 4 5 6 7