Linking GPS to Simrad IS15 instruments and to Open CPN

[TSB240]

I have had a busy weekend trying to get instruments to talk to my pc running open CPN and an old MLR gps.

I have managed to get the gps to feed the Simrad instruments and to get the robolinked simrad instruments to talk to the PC. I used the NMEA input port on the main combi instrument to connect the old MLR gps and used the spare nmea port on the wind instrument to talk to the PC.

However there remains a problem.

I can see the nmea sentences being read by the PC in the Nmea diagnostic window of open CPN

The boat position is found from the gps and is shown correctly on openCPN on the PC .

However the boat Icon is quite rapidly cycling from Red to Black and back and the satellite receiving signal indicator at the top right cycles the same from red to green and back as if open cpn is losing the GPS sentences and thus position for a varying time from 10-30 seconds.

Is it possible that additional NMEA sentences from the Simrad instruments Depth, Boat speed and wind speed sentences are somehow blocking the sat nav info.


Any thoughts... Much appreciated.

 

[AngusMcDoon]

I have had a busy weekend trying to get instruments to talk to my pc running open CPN and an old MLR gps.

I have managed to get the gps to feed the Simrad instruments and to get the robolinked simrad instruments to talk to the PC. I used the NMEA input port on the main combi instrument to connect the old MLR gps and used the spare nmea port on the wind instrument to talk to the PC.

However there remains a problem.

I can see the nmea sentences being read by the PC in the Nmea diagnostic window of open CPN

The boat position is found from the gps and is shown correctly on openCPN on the PC .

However the boat Icon is quite rapidly cycling from Red to Black and back and the satellite receiving signal indicator at the top right cycles the same from red to green and back as if open cpn is losing the GPS sentences and thus position for a varying time from 10-30 seconds.

Is it possible that additional NMEA sentences from the Simrad instruments Depth, Boat speed and wind speed sentences are somehow blocking the sat nav info.


Any thoughts... Much appreciated.

Sounds like the time OpenCPN waits until it thinks it has lost its input is less than the rate at which the required message is arriving. Check in the data stream window. If this timeout value is not a settable value in OpenCPN it should be. Suggest it to them to add as a feature. OpenCPN is only as good as the feedback it gets from users.

 

[TSB240]

Sounds like the time OpenCPN waits until it thinks it has lost its input is less than the rate at which the required message is arriving. Check in the data stream window. If this timeout value is not a settable value in OpenCPN it should be. Suggest it to them to add as a feature. OpenCPN is only as good as the feedback it gets from users.

Thank you sir.

Yep I have watched the data stream window and it does seem to respond to an incoming position signal after it has timed out.
I had thought something along those lines. Will post on the Open Forum and see if there is any way of increasing the timeout value.

As a matter of interest do you happen to know what sort of can bus or communications protocol (Simrad call it Robolink) is being used to link the Simrad IS15 instruments?


Steve

 

[AngusMcDoon]

As a matter of interest do you happen to know what sort of can bus or communications protocol (Simrad call it Robolink) is being used to link the Simrad IS15 instruments?

No. I hadn't even heard of it.

 

[rogerthebodger]

I have OpenCPN connected to my IS11 simrad instruments.

I The output is in my case NMEA 0183 connected into my computer via a RS232 to USB. I also have a Simrad plotter the outputs GPS data into the same system but for OpenCPN I am using a USP GPS mouse for the GPS location and the Simrad derived GPS position only as a secondary imput. My ais also has a seperate RS232 USB input into the computer. The AIS ,Simrad GPS and instruments are through a USB hub but the GPS mouse is a direct USB connection. I am using Navmonpc to collate the data and pass it to OpenCPN through a vertural port. This has the same effect as a multiplexer for the NMEA data messages.

My GPS mouse speed is 4800bps the instrumentation data is also 4800bps and the AIS is the standard 38400bps and Navmonpc handles the different speeds OK

My understanding of robonet is that it is also NMEA 0183 but robonet is only refered too in the case of my Simrad autopilot and not the IS11/12 instruments.

I think the only difference between IS11 and 12 is that graphical displays are used on IS12 and IS15 has the dataline X box included into one of the master displays but I stand to be corrected on that one.