Furuno ECDIS FMD-3200 Installation Manual page 62

2. WIRING
2.7.2 When the Raytheon Anschutz Steering Gear System will not be
used
When the Raytheon Anschutz Steering Gear System will not be used, take the follow-
ing measures to detect and announce autopilot interface failure.
• The preferred method is to use the 4-20mA output of the track control system when
the steering gear control system provides the failure detection and response as de-
scribed below. This method requires only the rudder order information and does not
require any additional status transfer between the autopilot and the steering gear
control system.
• The second best method is to use ±10V when the steering gear control system pro-
vides the failure detection and response as described below. Compared to the 4-
20mA interfaced an additional failure input is required in the steering gear control
system.
• The use of an additional analog memory device requires a failure input in order to
activate the memory function and a switch over of the rudder order from the track
control system (in their case the Autopilot Interface AS) to the analog memory de-
vice. This method should only be used if the steering gear control system does not
provide the functions as described above.
Failure of the Autopilot Interface AS and interface system type
What occurs when the Autopilot Interface AS fails depends on the type of interface
system used.
 4-20mA interface
• System failure alert generated.
• Rudder order from the Autopilot Interface AS to the steering gear control system
goes to 0mA
• The steering gear control system detects a failure as 0mA is an invalid value.
• Steering gear control system maintains the rudder angle.
 ±10V interface
• System failure alert generated.
• Rudder order from the Autopilot Interface AS to the steering gear control system
goes to 0V.
• Input of the system failure alert to the steering gear control system.
• Steering gear control system maintains the rudder angle.
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