TZT2 canbus comms issue

[GUNNIN]

This seems to be an intermittent problem. its happened 3 times now recently & presently staying at fault.

The system is;
3 devices networked by Ethernet which appear to be communicating;
TZTL15F (me)
DRS4D-NXT
FA-50 ( i believe this unit has a separate roof mounted GPS ant)

Another 6 devices connected by CanBus FI-5002 junction box which are powered but do not appear to be talking???;
PG-700
GP-330B
FI-70
IF-NMEA2K2
NAVpilot-700
711C

The problem;

The FI-70 display and 711C auto pilot are powered up but not displaying lat/long, as they did before.
The FCV-295 is not displaying speed which is fed from the IF-NMEA2K2 converter, as it did before.

There are two roof mounted GPS antennas, the 330B is connected to the FI-5002 canbus & was selected as the GPS source in the TZT2. the other GPS i think may be directly connected to the FA-50 AIS. dont know its model, it doesn't appear in sensor list.

Its seems like the FI-5002 canbus network has stopped talking. The TZT is displaying lat long from its internal GPS (or maybe its getting it from the FA-50?) but we cant get lat long from the GP-330B on roof, as we did before.
When we selected the TZT to be the gps source it didn't share lat long with other devices on CanBus network.

All devices on the canbus network are connected to a FI5002 junction box. there isn't any backbone cabling so both terminating resistors in the FI5002 are on. I checked for power at JB supply terminals, 12v all good. I checked power on red black at the plugs of each device at JB all good 12V, each Blue White pair at JB has 3V.

Thinking about my previous statement of course all those terminals will have same voltages as the fi5002 parallels everything, doesn't it?

All the Can Bus devices are listed on the SENSOR list at "INSTANCE 0" and appeared to be greyed out. does that mean there not talking?

After i did a reset of the sensor list all the canbus sensors disappeared.

i believe this to be a loose wire type issue as it happened when we were stuffing about trying to fix a wiring issue with the FCV-295. thats now fixed. I think we disturbed something.

So my i guess my question is what the best way to fault find the canbus cabling?

Or is there a way to select different devices in the TZT2 to help indicate where the wiring issue is?

Any advice appreciated.

Mark

 

[GUNNIN]

devices in the sensor list seem to come and go

 

[GUNNIN]

3 more screen shots,


FA50 is the GPS source in this shot, its usually has the 330B selected. not sure if unit changed over to FA50 by itself or the operator selected it.

FI-70 & 330B greyed out not communicating

FI-70 now communicating & 330B still greyed out.
This is random, just does this by itself without touching any cabling. Yesterday all Canbus devices were greyed out.

 

[GUNNIN]

a couple more screen shots of Data Source page. I think everything was working fine when these photos were taken.

330B selected as gps source this time.

 

[Johnny Electron]

Have you turned off the NMEA 2000 power and ohmed out the bus (between BLUE and WHITE)? What value do you read?

 

[GUNNIN]

Have you turned off the NMEA 2000 power and ohmed out the bus (between BLUE and WHITE)? What value do you read?

No, ill try that later in the week, is there a figure to expect?

 

[Johnny Electron]

60 ohms

 

[GUNNIN]

60 ohms

OK it is 60 ohms. I removed one of the termination resistor jumpers and it went up to 120 ohms so I assume the 2 resistors are 120 ohm ea in parallel.

New development, during water testing we found that Canbus network came good when we unplugged the GP-330B. after that everything worked perfectly all day, using the F-50 as the GPS source.

Plugging it back in crashed the network instantly.

So were pretty sure the 330B is toast and is crashing the network.

I did some resistance readings of the blue white on the unplugged 330B. 3Mohm, 50Kohm, 3Kohm, it seemed to vary. Not sure what the correct reading should be.

 

[Johnny Electron]

It sounds like the GPS or cable it is using has a problem. Good troubleshooting.