CP31/CX33/34/44/54

Loss of position update and water speed data from SimNet

Error report
From the field we have received reports that the
Simrad NavStation would cease to update and
supply a GPS position, or would lose e.g. water
speed update from IS15.

Loss of position
The CX44/54 NavStation would suddenly stop
updating the position on the chart and sending out
position data to other connected products. By
entering the interface setup you could see that the
Group selection was still SIMRAD, but Position
mode had changed from INTERNAL to
EXTERNAL.

Explanation
Simrad products connected via SimNet will as
standard form a Simrad Group, meaning that all
instruments will refer to same source for each
function. Simrad NavStation or Chartplotter will
automatically be the position source. However,
the position mode: INTERNAL / EXTERNAL of
the NavStation, can be controlled via commands
on the SimNet and an unintended command may
therefore force the NavStation to change position
source.

When the autopilot is switched on it draws a fairly
heavy current and the voltage drop makes the
AT44 perform a controlled reset. The reset
commands will collide with the start-up routines
within the autopilot, which, in this special
situation, will send out a new command telling the
system that it is now the position source for the
Simrad Group.

Instant remedy
Change the SimNet setting of the autopilot to
STAND-ALONE.
If the position setup of the NavStation is changed
to EXTERNAL as described, a Global reset of
SimNet should resume normal operation.
A Master Reset of the NavStation and Autopilot is
only to be applied if normal operation is not
achieved via the global SimNet reset.

Short term remedy
As underlined in the installation instructions for
SimNet, the power source to the network has to be
stable and should not be shared with power
consuming devices such as start motor, bow
thruster, autopilot, chart plotters, VHF etc..

Long term remedy
The next release of software for the autopilots is
scheduled to come within one month and will
include routines to prevent unintended change of
data sources.

Loss of water speed data from IS15/AT15
Observation: Water speed and other data from
IS15/AT15 are not updated on the NavStation, but
replaced by *** although it is shown correctly on
the instrument. The problem is presently being
analyzed and a new bulletin will follow shortly
after this one.

Regards Frank