Nmea signal monitor, Nmea port test (ac hardware) – Simrad AP25 User Manual
Page 132

Simrad AP25 Autopilot
130
20221495F
For all data items, one of the following codes will be displayed: 
– – – No data or no NMEA sentence containing the data 
 needed is available at the input port. 
OK Valid data found 
INV Message with invalid information. 
FRM Message has format failure such as 
a) Incorrect check sum 
b) Wrong contents in datafield(s) 
If data are missing or invalid, perform the following: 
• Check the NMEA signal monitor (see below) 
• Open the source select page in the User Setup2 menu and 
check that data are available
• Check the navigator setup and make sure it is transmitting
appropriate data.
• Perform a NMEA Port Test (hardware) as per below.
Note !
The “WIND” reading is the apparent wind from port (L) or 
starboard (R). The “SPEED” reading is the speed through 
water. 
NMEA signal monitor
Near the NMEA terminals in the Autopilot Computer you will 
find a green monitor LED marked “RX”. A flickering LED 
indicates that a NMEA signal is received. It does not, however, 
qualify the contents of the message. 
Note !
Do not mix up the “RX” LED with the LED marked “TX”. The 
“TX” LED will always be lit or flickering when the autopilot is 
on. 
NMEA Port test (AC hardware)
Disconnect the cables on the Main PCB in the Autopilot 
Computer and connect TX1+ to RX1+ and TX1- to RX1-. 
Similarly, on the Power PCB connect the NMEA ports the same 
way; TX2+ to RX2+ and TX2– to RX2–. 
