Nmea 0183 query

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Daydream believer

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My AIS is connected to my chart plotter via NMEA 0183.baud 4800 is set on both units
Plotter is a Lorenz. AIS is Amec Camino 101
The chart plotter keeps cutting out at irregular intervals- days sometimes hours or minutes-requiring me to go through the start procedure, set route etc etc which takes a couple of minutes. Then I have to wait for the AIS signal to re load & relocate the targets
I am wondering if this is an AIS plotter mis match although I was sold the pair together. the supplier can find no issue with the plotter. They left it turned on with no ais connected for 2 weeks & it did not fail.

I have just noticed that the instructions for the AIS states that the max length of the NMEA cable should be 1.5 metres & the manufacturers state performance will be impaired if greater.
I have it 4 metres long as the plotter sits behind the tiller on a base station where I can access it.
So first question
Is there a way to boost the NMEA signal if the problem is due to a wire being too long. Would that be an issue?

The next issue is that the wiring diag for the AIS shows 4 wires from the NMEA output
RXP
RXN
TXP
TXN
I have taken 2 wires ( not sure which 2 as I do not understand what the above means) as I was advised by the supplier & put them into one port of the plotter.
Second question
There are 2 more plotter ports. Should I be using 4 NMEA wires into the plotter in lieu of the 2
I note that the plotter does not show all the info that the AIS is capable of showing - Icons etc- is it because I should have more wires connected

Any comment appreciated
Thanks
 
Last edited:
Are you sure the bit rate is 4.8Kb? AIS is normally 38.4Kb because the messages are too large and too frequent to be transmitted using 4.8Kb.

If you really are using 4.8Kb I'd expect you'd lose a considerable proportion of the messages and probably have buffering problems at the transmitter end.
 
Following your query I have just checked the manual again & AIS has 2 baud rates 38400 & 4800 plotter has 1200, 4800 & 9600 ----so both were set to 4800. Presumably from what you say that is why i do not get the full range of options showing up on the plotter.
 
Daydream believer said:
Following your query I have just checked the manual again & AIS has 2 baud rates 38400 & 4800 plotter has 1200, 4800 & 9600 ----so both were set to 4800. Presumably from what you say that is why i do not get the full range of options showing up on the plotter.
Click to expand...

I suspect that as well as missing data you'll also get less frequent target updates, especially when there's a lot of AIS traffic about. By "Lorenze" do you mean "Lowrance"?
 
Daydream believer said:
Following your query I have just checked the manual again & AIS has 2 baud rates 38400 & 4800 plotter has 1200, 4800 & 9600 ----so both were set to 4800. Presumably from what you say that is why i do not get the full range of options showing up on the plotter.
Click to expand...

I'd agree with lpdsn and macd. The density of incoming information from an AIS receiver is such that 38400bps is adequate. Nothing slower will work very well, if at all. That's why the Camino-101 offers that speed. I think the other port speed is to allow incoming GPS data at the the OLD standard of 4800bps to be merged in the receiver.
What model is your plotter?
We had an old Garmin plotter once with 2 NMEA 0183 ports. ONE of which could be set to 38400 for AIS.
If your plotter has more than one NMEA 0183 port you could just be lucky with speed options. ? Otherwise it is unlikely that you will get decent AIS display on the plotter. Check the manual in detail?
 
Daydream believer said:
My AIS is connected to my chart plotter via NMEA 0183.baud 4800 is set on both units
Click to expand...
Likewise I'm surprised. And I wouldn't be surprised if that is the source of crashes... To much data at once...?


I have just noticed that the instructions for the AIS states that the max length of the NMEA cable should be 1.5 metres & the manufacturers state performance will be impaired if greater.
I have it 4 metres long as the plotter sits behind the tiller on a base station where I can access it.
Click to expand...
Possibly. Although 1.5m feels short. What is your cable made of? That would also affect things.

Any reason the AIS can't be closer?

So first question
Is there a way to boost the NMEA signal if the problem is due to a wire being too long. Would that be an issue?
Click to expand...
I guess a multiplexer **might** in the middle. But if it received crap it will send crap.
The next issue is that the wiring diag for the AIS shows 4 wires from the NMEA output
RXP
RXN
TXP
TXN
Click to expand...
I'd take that as
Receive +ve
Receive -ve
(These would take another NMEA data source and pass it through with the AIS data. At 4800 I doubt there is capacity, and it doesn't sound like you need it.)
Transmit +ve & -ve are the AIS sending data out .


There are 2 more plotter ports. Should I be using 4 NMEA wires into the plotter in lieu of the 2
Click to expand...
No!

I note that the plotter does not show all the info that the AIS is capable of showing - Icons etc- is it because I should have more wires connected
Click to expand...
More likely the 4800 limits data, OR the plotter can't handle it...

If you have a laptop... ...with a com port (or a USB to Com lead) you could capture all the NMEA data... Which would let you investigate if something is missing... It would also let you simulate the sent data to see what causes it (wire length, specific data etc)... #GoodLuck
 
ShinyShoe said:
More likely the 4800 limits data, OR the plotter can't handle it...

If you have a laptop... ...with a com port (or a USB to Com lead) you could capture all the NMEA data... Which would let you investigate if something is missing... It would also let you simulate the sent data to see what causes it (wire length, specific data etc)... #GoodLuck
Click to expand...

That is a point. The AIS has a computer lead & when connected it can overlay onto a laptop chart or radar display etc I will connect & see what comes from the AIS & compare with the plotter

the plotter does give basic stuff like vessel details Name MMSI direction CPA & TCPA but doe not display type, rate of turn, & most of the icons that the AIS can display, inc friendly ships, & heading lines & colour for those likely to be close encounters
 
Last edited:
Daydream believer said:
Following your query I have just checked the manual again & AIS has 2 baud rates 38400 & 4800 plotter has 1200, 4800 & 9600 ----so both were set to 4800. Presumably from what you say that is why i do not get the full range of options showing up on the plotter.
Click to expand...

The plotter manual is ambiguous, in one place it says it supports 4800 and 38400, in another it says 4800 and 9600. Can you go into the menu on the plotter and verify ?
 
Daydream believer said:
My AIS is connected to my chart plotter via NMEA 0183.baud 4800 is set on both units
Plotter is a Lorenz. AIS is Amec Camino 101
The chart plotter keeps cutting out at irregular intervals- days sometimes hours or minutes-requiring me to go through the start procedure, set route etc etc which takes a couple of minutes. Then I have to wait for the AIS signal to re load & relocate the targets
I am wondering if this is an AIS plotter mis match although I was sold the pair together. the supplier can find no issue with the plotter. They left it turned on with no ais connected for 2 weeks & it did not fail.

I have just noticed that the instructions for the AIS states that the max length of the NMEA cable should be 1.5 metres & the manufacturers state performance will be impaired if greater.
I have it 4 metres long as the plotter sits behind the tiller on a base station where I can access it.
So first question
Is there a way to boost the NMEA signal if the problem is due to a wire being too long. Would that be an issue?

The next issue is that the wiring diag for the AIS shows 4 wires from the NMEA output
RXP
RXN
TXP
TXN
I have taken 2 wires ( not sure which 2 as I do not understand what the above means) as I was advised by the supplier & put them into one port of the plotter.
Second question
There are 2 more plotter ports. Should I be using 4 NMEA wires into the plotter in lieu of the 2
I note that the plotter does not show all the info that the AIS is capable of showing - Icons etc- is it because I should have more wires connected

Any comment appreciated
Thanks
Click to expand...

Regarding cable length, my nmea cable from my Digital Yacht AIS receiver is 6m long and works perfectly.

Www.solocoastalsailing.co.uk
 
Last edited:
According to a Lorenz Compact X7 user manual I found by Googling; the AIS can be set to 34800 baud.

Page 100;

5.7.3 TO SET THE CHART PLOTTER FOR RECEIVING AIS
Make sure that the AIS receiver is properly connected to the chart plotter.
The chart plotter reads the AIS NMEA message VMD, type 1, 2, 3 and 5.
Select the used serial port and transmission speed by following the procedure:
'MENU' + "BASIC SETTINGS" + 'ENTER' + "INPUT/OUTPUT" + 'ENTER' +
"PORT n INPUT" + 'ENTER' + "m" + 'ENTER'
User Manual 101
Where: n = Port 1/Port 2/Port 3
m = NMEA-0183 4800-N81-N , NMEA-0183 38400-N81-N
according to the transmission speed of your AIS receiver.
5.7.4 QUICK INFO ON AIS TARGET
By placing the cursor over a AIS target icon, the following information is displayed:
• Vessel Name
• MMSI number
• Radio Call Sign
• SOG
• COG
• CPA and TCPA values
Note
The selected AIS target icon is surrounded by a square frame when user places the cursor over the icon.
 
Suddenly my replies to Paul rainbow & John GC have gone astray
have I been blocked? let's see if this post comes up!!
if not thanks to you both I will check my plotter this afternoonif i can get to the boat
In the meantime the wiring is confusing because 2.5.3 shows 3 NMEA wires from an NMEA 0183 device going to 4 points in the plotter
My AIS has 4 wires
 
JohnGC said:
According to a Lorenz Compact X7 user manual I found by Googling; the AIS can be set to 34800 baud.

Page 100;

5.7.3 TO SET THE CHART PLOTTER FOR RECEIVING AIS
Make sure that the AIS receiver is properly connected to the chart plotter.
The chart plotter reads the AIS NMEA message VMD, type 1, 2, 3 and 5.
Select the used serial port and transmission speed by following the procedure:
'MENU' + "BASIC SETTINGS" + 'ENTER' + "INPUT/OUTPUT" + 'ENTER' +
"PORT n INPUT" + 'ENTER' + "m" + 'ENTER'
User Manual 101
Where: n = Port 1/Port 2/Port 3
m = NMEA-0183 4800-N81-N , NMEA-0183 38400-N81-N
according to the transmission speed of your AIS receiver.
5.7.4 QUICK INFO ON AIS TARGET
By placing the cursor over a AIS target icon, the following information is displayed:
• Vessel Name
• MMSI number
• Radio Call Sign
• SOG
• COG
• CPA and TCPA values
Note
The selected AIS target icon is surrounded by a square frame when user places the cursor over the icon.
Click to expand...

AIS message types 1,2,3,5 are the most useful.
The current trend for Static Aids to Navigation to have AIS positions is not supported by many plotters yet. (Message 21 in that case)
Many AIS receivers filter out those "other" messages.

All available are described here : https://www.navcen.uscg.gov/?pageName=AISMessages
 
Daydream believer said:
That is a point. The AIS has a computer lead & when connected it can overlay onto a laptop chart or radar display etc I will connect & see what comes from the AIS & compare with the plotter
Click to expand...
Mmm... If this lead is on a different port you aren't seeing exactly what the plotter does. It's a useful starting point but remember they may differ.

the plotter does give basic stuff like vessel details Name MMSI direction CPA & TCPA but doe not display type, rate of turn, & most of the icons that the AIS can display, inc friendly ships, & heading lines & colour for those likely to be close encounters
Click to expand...
Some of that may depend what the vessel is sending. If it's Class B you won't get a rate of turn and it might mean a load of class B's all look very similar?

A RasPi in the middle would be a cheap solution (£50) for doing the diagnostics..but then you'd just replace the plotter with OpenCPN :)
 
Daydream believer said:
Suddenly my replies to Paul rainbow & John GC have gone astray
have I been blocked? let's see if this post comes up!!
if not thanks to you both I will check my plotter this afternoonif i can get to the boat
In the meantime the wiring is confusing because 2.5.3 shows 3 NMEA wires from an NMEA 0183 device going to 4 points in the plotter
My AIS has 4 wires
Click to expand...

Your AIS has a single port.
Your plotter has two ports.

Each port can transmit and/or receive.
Each port has four wires, a pair for TX and a pair for RX..

You need to connect the two TX wires from the AIS to the two RX wires on one of the plotter ports. You do not need any more than two wires to be connected to receive AIS at the plotter. Hopefully you can set both devices to 38400.

It is true that some devices only have the + wire for each port, the - uses the -12v. Yours are not this type, so you should also connect the - wires.
 
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