Operating Instructions and Installation Instructions

ComNav Vector G2/G2B Installation & Operation Operation
Document PN 29010078 V2.0 - 48 -
DRAFT #3 – 29 May 2009
Baud Rate
All ComNav autopilots (and all marine equipment which is compliant to the NMEA 0183
Standard) communicate at 4800 Baud, for both input & output
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.
But, although the NMEA Standard specifies 4800 Baud
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, it is common for “NMEA
compatible” equipment to be able to work at higher speeds (especially at RS-232 levels).
Each of the Vector G2’s two output ports can be configured, independent of each other,
to communicate at all conventional Baud rates from 4800 up to 38400 Baud.
• The factory-default configuration of both Ports A & B is 4800 Baud.
Note: for operation with all ComNav autopilots, the G2’s factory-default
Baud rate of 4800 must be used. For operation with other equipment,
other Baud rates may be allowable, depending on the equipment.
Electrical Interface
Another factor in using the G2 is what type of the electrical interface (i.e., signal levels,
rise/fall times, circuit impedances) the other equipment uses for its Input/Output
“navigation data” connections.
All marine equipment which is fully compliant with the NMEA 0183 Standard (e.g.,
ComNav autopilots) uses RS-422 levels only.
Other on-board “NMEA compatible” equipment – e.g., PCs – often uses RS-232 levels.
Each of the G2’s two output ports is available at both RS-232 & RS-422 electrical levels;
the RS-232 and RS-422 output signals may be used simultaneously (see Serial Ports on
page 28 for more details).
Not
e
: on each port, the sentences that the port is configured to output,
their update rates, and the port’s Baud rate, will be the same, for
both the RS-232 and RS-422 signals from that port.
Alarm Output
In addition to the data output on the G2’s two serial ports, there is a separate Alarm
output, which indicates whether or not the G2 is providing valid heading output data.
An Alarm relay is located on the G2’s circuit board. The relay’s contacts are isolated
from all circuitry in the G2 – the G2’s internal processor controls the coil side of the relay,
but the contacts of the relay are connected only to the two Alarm pins on the G2’s I/O
connector.
If the G2 is unpowered, or if it is powered but is not able to compute valid heading data
(for example, when it does not have good GPS signals at one of the two antennae), the
relay coil is de-powered. This causes the relay contacts to open – which can then
activate whatever system you wish to use to indicate a Loss-of-Heading condition.
When the G2 is powered, and when its heading output data is valid, the relay coil is
powered by the G2’s processor, which closes the relay contacts; this indicates that the
G2 is operating correctly.
Watchdog
A watchdog timer is controlled by software in the G2, and is triggered when heading
becomes invalid for any reason. If the heading remains invalid for a long enough time,
the watchdog timer causes the Alarm relay’s contacts to open.
The watchdog software is in compliance with IEC 60495.
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The Commander P2 and the Admiral P3 can optionally work at Baud rates up to 9600 Baud on their NAV2 Inputs,
but only with certain equipment (in particular, only with the first generation of the G2, see page 89).
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A supplemental standard, NMEA 0183-HS specifies operation at 38,400 Baud.
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