SeaTalk hs

[Graham_Wright]

I have recently had to change my cockpit located E80 plotter as it became "a little damp".
Now I have found that the replacement does not talk to the nav position plotter.
Bringing everything below and permuting plotters and cables, I have drawn a blank.
All three plotters work as expected (including the "damp" one) but there is no communication between slave and master.
The ethernet connection requires a crossover of cores This could be the culprit but checking the connections single handed I have found impossible.
As I have a fish finder, DSM, which has never been connected, I have acquired a SeaTalkhs switch.
I expected this to have seven inputs and one output that included the crossover for connection to the master plotter.
I have found no such distinction. The down loaded manual offers no help.
Please somebody elucidate.

 

[[164147]]

You don't use a crossover connector when you use a switch.

All units must be on the same software version to be networked.

 

[Caladh]

I have recently had to change my cockpit located E80 plotter as it became "a little damp".
Now I have found that the replacement does not talk to the nav position plotter.
Bringing everything below and permuting plotters and cables, I have drawn a blank.
All three plotters work as expected (including the "damp" one) but there is no communication between slave and master.
The ethernet connection requires a crossover of cores This could be the culprit but checking the connections single handed I have found impossible.
As I have a fish finder, DSM, which has never been connected, I have acquired a SeaTalkhs switch.
I expected this to have seven inputs and one output that included the crossover for connection to the master plotter.
I have found no such distinction. The down loaded manual offers no help.
Please somebody elucidate.

Did u replace the E80 with same or summat else and if summat else, DrSpocks answer is relevant even if u replaced with same.

 

[Graham_Wright]

You don't use a crossover connector when you use a switch.

All units must be on the same software version to be networked.

As an engineer who has wrestled with various data comms in the past, can you explain why? I am interested.

 

[[164147]]

Compatibility. Different software versions may introduce different features and or data / error handling. It's simpler to ensure devices run the same OS.

 

[lustyd]

As an engineer who has wrestled with various data comms in the past, can you explain why? I am interested.

It's a (very) legacy thing. Crossover was traditionally used for point to point connections while straight through was used for switched (and I think hubs) connections. That all went away some time around the turn of the century when MDI was added, allowing the port to auto-sense and crossover as needed.

The reason is simple, one is transmit and one receive, so you don't want one to transmit to the other's transmit wire.

 

[PaulRainbow]

It's a (very) legacy thing. Crossover was traditionally used for point to point connections while straight through was used for switched (and I think hubs) connections. That all went away some time around the turn of the century when MDI was added, allowing the port to auto-sense and crossover as needed.

The reason is simple, one is transmit and one receive, so you don't want one to transmit to the other's transmit wire.

As the ports auto-sense, is it not therefore the case that it wouldn't matter if a crossover cable was used, as the OP did ?

In the case of marine MFDs crossover cables were need for point to point connections much later than you think. Raymarine widescreen MFDs, needed crossover cables, as did Garmins 4000 series.

 

[lustyd]

As the ports auto-sense, is it not therefore the case that it wouldn't matter if a crossover cable was used, as the OP did ?

I would guess that, but as you say these devices weren't exactly up to date with hardware and software so entirely likely they still would need one. Only one end needs to support MDI though, so when paired with something newer the other device would sort out the crossover issue.

 

[Graham_Wright]

I am on board and have just checked the ethernet cable selection I have. The Raymarine sourced ones have cores 1, 2, 3 and 6 connected (pus screen). The others (out of the workshop drawer) have 1 - 8 connected (and no screen). Neither have crossed over connections.
I hope the terminations have opto isolators or some other protection.

 

[lustyd]

It’s likey the Raymarine is 10Mb rated where not all connections need to be made so don’t read too much into that. Half of the connectors in Ethernet are noise reduction anyway in twisted pairs with the other half.

 

[[164147]]

Raymarine uses T568B termination - the connectors require a shield.

 

[Graham_Wright]

Success!
Using cables with the screen works.
My, aren't they expensive!

 

[Graham_Wright]

Thinks - with only 8 available pins, how does the screen make contact? Are the shrouds metallic?

 

[lustyd]

A shielded connector has metal on the body which touches the shielding in the cable. I’ve never seen the shielding enforced in any scenario, it’s more likely a bad crimp was to blame. Ethernet almost always negotiates speed to whatever the cable handles and marine systems never need enough bandwidth for shielding to matter, they’re usually 10 or 100Mbps.
Cat5 connectors are the best for DIY as they’re much easier to match to a given cable and therefore easier to get a good crimp. Newer connectors have different wire gauge sizes and will often fail to crimp properly as a result because cat5 cable cores are too skinny so the prongs miss. Marine folk won’t be using more modern cable gauge as they aren’t doing power over the Ethernet, they’re just add some DC cores usually.

 

[Chiara’s slave]

A shielded connector has metal on the body which touches the shielding in the cable. I’ve never seen the shielding enforced in any scenario, it’s more likely a bad crimp was to blame. Ethernet almost always negotiates speed to whatever the cable handles and marine systems never need enough bandwidth for shielding to matter, they’re usually 10 or 100Mbps.
Cat5 connectors are the best for DIY as they’re much easier to match to a given cable and therefore easier to get a good crimp. Newer connectors have different wire gauge sizes and will often fail to crimp properly as a result because cat5 cable cores are too skinny so the prongs miss. Marine folk won’t be using more modern cable gauge as they aren’t doing power over the Ethernet, they’re just add some DC cores usually.

PoE runs on the same cores as 10/100 Ethernet (1,2,3 and 6). Gb Ethernet uses the other 4 cores as well, but, as it’s backwards compatible, uses the same power cores. Just for completeness.

 

[lustyd]

PoE runs on the same cores as 10/100 Ethernet (1,2,3 and 6). Gb Ethernet uses the other 4 cores as well, but, as it’s backwards compatible, uses the same power cores. Just for completeness.

It can, yes. Higher power needs newer cables with thicker cores though and thats mostly what has changed in recent updates. The Cat5 spec would suffer voltage drop if too much power were transferred.
Similar story with USB

 

[Chiara’s slave]

It can, yes. Higher power needs newer cables with thicker cores though and thats mostly what has changed in recent updates. The Cat5 spec would suffer voltage drop if too much power were transferred.
Similar story with USB

I haven’t used cat 5 for 15 years, it’s all been cat6. That is I believe still compliant with the latest power specifications. Though I have yet to try a PoE device that can’t run on cat5. 4k hdmi over cat is often 24w, that works.

 

[lustyd]

I haven’t used cat 5 for 15 years, it’s all been cat6. That is I believe still compliant with the latest power specifications. Though I have yet to try a PoE device that can’t run on cat5. 4k hdmi over cat is often 24w, that works.

That doesn’t change anything about what I said.

 

[Chiara’s slave]

That doesn’t change anything about what I said.

You seem a little unclear about cable. Fortunately this doesn’t matter, most folks will just buy a marine grade Ethernet cable with the rubber boots demanded by the instrument manufacturers warranty. The cables themselves may well be cat 6 compliant these days, they often don’t say. Shielded cable is obviously thicker and stiffer anyway. The rubber boot bit is capitalised in my Garmin plotter’s handbook. Your warranty is invalid unless you use a branded Garmin cable. Clearly there’s nothing technically different, it’s the seal between cable and socket.

 

[lustyd]

You seem a little unclear about cable. Fortunately this doesn’t matter, most folks will just buy a marine grade Ethernet cable with the rubber boots demanded by the instrument manufacturers warranty. The cables themselves may well be cat 6 compliant these days, they often don’t say. Shielded cable is obviously thicker and stiffer anyway. The rubber boot bit is capitalised in my Garmin plotter’s handbook. Your warranty is invalid unless you use a branded Garmin cable. Clearly there’s nothing technically different, it’s the seal between cable and socket.

I’m not unclear at all, I spent many years building out data centres. The cables usually do say and most of them are some kind of Cat5, some are Cat6 but with thin cores like Cat5. Shielding doesn’t make the cable thicker, it’s extremely thin foil in most instances since we’re still talking old style cables.
Yes, Garmin don’t support you with DIY cables, and waterproofing is compromised. Obviously! With my B&G I had one long cable and put the OEM ends outside with standard RJ45 in the dry electronics cupboard in the non marine switch. If that gets wet all the electronics are off anyway.