More Simnet / N2K questions!

[Scott T-Bird]

Alright, I've put my new N2K backbone system together for B & G products and it is all pretty much plug & play without any complications. I mentioned before that I have 2 NMEA 0183 devices that I also want to connect into the backbone. I have an IS 12 wind display and a WP-30 wheel pilot, which according to the Simnet Manual, they are both Simnet Class 2 products but the WP does not have Simnet connections (instead, there are 4 wired connections for data and 2 wires for power).

I bought the AT-10 conversion device and the Micro-C (male) to Simnet cable and plugged them into the backbone to see how it works. In the meantime, I spoke with a B & G/Simrad service tech and got some information, but he seemed a little fuzzy on the finer points, so in the end, I still have questions. Here's what I found.

The IS 12 display has 2 Simnet ports. One is the data port that is connected with a yellow tip Simnet cable. The other port is for the power (pos & neg) connection and a red tip Simnet cable is used to feed power. The red tip indicates that the power feed is also a termination.

The AT-10 has 2 Simnet ports and 4 wires. The wires are used to connect devices that do not have Simnet ports, such as the WP. 2 wires are Rx (receivers) and 2 wires are Tx (transmitters). When I plug the Micro-C / Simnet cable into the AT-10, a little green light goes on indicating power is supplied (supplied from my N2K backbone). I then connected the IS 12 display with a Simnet cable. I got power on the display, but unfortunately, no wind data from the wind transducer. Well, I know what that problem is … I only had 1 Micro-C/Simnet cable and I need it for the wind transducer, so I had to buy another one so I can connect the transducer and the converter/IS 12 display into the backbone at the same time. I just got it and have to wait for an opportunity to try it. But the fact that the display is powered via the N2K backbone and the AT-10 leads to my questions.

Do I no longer need to use the red-tip power cable to provide power to the IS 12 display? Can I simply leave that port open or does it now need a termination plug? The Simnet manual provides no explanation for these questions. Neither did any of the internet sources that have been referenced, such as Panbo, provide explanation for these details. Instructions are similarly stunted!

Other questions: The Simnet Manual indicates that a separate AT-10 should be used for each 0183 device. However, the tech rep indicates that a single AT-10 can be used for two "listeners" (More than 1 "talker" would be a problem). I'm thinking that the WP and IS 12 display are both "listeners" The WP has 4 wires, 2 are for GPS input and 2 are for Compass input. The 2 GPS input wires will obviously be connected to the 2 Tx wires from the AT-10. Should I assume that means that the compass input wires must also be connected to Tx wires from possibly a second AT-10 in order for the compass input to be utilized by the WP? I don't see that there is any data from the WP or IS 12 display that will be "received" by the N2K system via the converter, so it would seem that the Rx wires from the converter would be unused?

 

[HMT2]

Scot,

Let me begin by saying I am ignorant in the ways of Simnet. However, I am fairly fluent in N2K. I know a variety of companies make 0183 to N2K converters. Is that what they micro C Simnet cables do. Here is a link to what I am talking about as far as converters. http://www.yachtd.com/products/nmea...MIs9r-g_r03QIVgtlkCh0vPwqWEAAYAiAAEgIHA_D_BwE

 

[Scott T-Bird]

Not exactly, the cable merely converts a Micro-C port to a Simnet port. The AT-10 converter is similar to the device you show, except that it uses Simnet ports and the 4 wires for devices that don't have the Simnet port.

 

[Stu Jackson]

Scott,Les Troyer is very good at this stuff. He's probably on his way back from Annapolis by plane, so be patient, or pm him with a link back here so he sees it. Good luck.

 

[LeslieTroyer]

Scott. The wind is a talker and the autopilot could be both but most likely just a listener.

Connect the wind to rx port on the 183 converter, and the autopilot to a tx port.

I’m not up on simnet but will look it up when I get back (Wed). Hope to see you in Feb with Stu for the winter sail.

Les

 

[Scott T-Bird]

I don't understand why the IS 12 display would be a "talker". It is only receiving input from the transducer, no? BTW, even if the display is a "talker" (it would be if transmitting to the WP), I don't need it to "say" anything. I only want it to display apparent wind and/or true wind data that it receives from the backbone.

The new Triton displays and chartplotter should be talking via the backbone.

I do want the WP-30 to "receive" GPS and "sail to wind" input from the backbone via the converter. In this case, since the WP is connected via wires, the converter will be wired to the WP via Tx wires.
Here is a description of the AT-10 device. http://www.chicagomarineelectronics.com/Simrad Documents/SimNet/AT10.pdf

What is not clear to me is how to make a connection to the IS 12 display. The picture shows the device with 2 Simnet Ports and a set of 4 wires. I have to use a Simnet cable to connect with the IS 12 display - it only has Simnet ports, there are no connection contacts for bare wires.

N2K has to come into the AT-10 via a Micro-C/Simnet (male) cable. That is how it is described to be done, and I have already verified that. Therefore, I must use the other Simnet port to run a cable to the IS 12 (if that is how it works). My question is … does the conversion from NMEA 2000 to NMEA 0183 take place between those 2 Simnet ports on the device??? Some descriptions of the device that I have seen show that the NMEA 0183 output is only thru the wires. That will work for the WP but it won't work for the IS 12 display, which only accepts a Simnet cable.

If the Simnet cable doesn't work to transmit to the IS 12 display, I simply can't use the display. It won't be a loss since I have 2 new displays anyway. I'd just have to remove the IS 12 display and find another use for that space on the bulkhead.

 

[HMT2]

So Scott, I had some similar issues with a new Raymarine Autopilot I put in. With the addition of the ev100 wheel,pilot i eleminated my last 01$3 instrument. My gut would be to use a 0183/N2K converter for each of you old 0183”s and plug into your N2K. As I said previously I have no Simnet experience but from what I’ve read it is like the Seatalk NG situation. Here is a link about the Seatalk NG / N2K thread. Don’t know if that will be at all helpful but here it is. A diagram might be helpful.

https://forums.sailboatowners.com/index.php?threads/seatalk-ng-demystified.182555/#post-1374040

 

[LeslieTroyer]

Scott to answer why your wind would be a talker is the wind sensors typically don’t talk 183 that is done in the head or display unit of the older devices. Your autopilot needs to know about aparent wind to stail by the wind. So the wind would need to talk the autopilot.

I don’t know what simnet uses for true wind but RM uses water speed not GPS. Still haven’t looked at the manuals yet maybe tomorrow

Les

 

[Scott T-Bird]

Hello Les! Ward sends his regards and was really happy to meet you folks! Me, I was disappointed that I could not be in Annapolis.

The only reason for me to link the IS 12 wind instrument is just to display wind data. As I've discussed, I have a new N2K backbone system with Triton transducers for wind and speed and new triton displays that all talk back and forth in their format with everything else in the network (new chartplotter, new VHF). My largest hope is that the converter will enable the data from the N2k backbone system to be fed in 0183 to the WP. It appears to be readily feasible.

I am probably just confusing things by talking about the old wind display. My old IS 12 display does not need to talk to the WP. It's just there because I have it and want to keep it in display. If I can use it, perhaps it is best to use a separate AT-10. The instructions show how multiple converters can be daisy-chained for multiple devices in 0183. In my case, it is just the WP and the IS 12 display. Hopefully, I will see how it works on Friday.

 

[Scott T-Bird]

Success! My questions have been answered. The backbone is all NMEA 2000. I still have the VHF and another Triton display to add to it. The green light on the converter indicates power is supplied. I was questioning if the N2K/0183 conversion occurs across the 2 Simnet ports and it does! Now I have my IS-12 Wind Display functioning, and even better, it now displays True wind and Apparent, not just Apparent. When the Wheel Pilot is installed, I should be able to send GPS positioning to the 0183 pilot via the Tx wires.

Also shown is my bulkhead grouping of displays with new Triton display upper right, IS-12 Wind upper left, and Data Marine depth and speed units. All are functioning well, so I leave the older ones in place for redundancy. I'm planning to group the other Triton display with the chartplotter … that's my next step.

As shown, the IS 12 has 2 Simnet ports. The original installation has one port for power and the other for data. Now that power is supplied by the backbone, the un-used port is simply not needed.

 

[LeslieTroyer]

Is there a terminator on your wind transducer?? You need one on both ends of your backbone.

 

[Scott T-Bird]

Is there a terminator on your wind transducer?? You need one on both ends of your backbone.

Yes, the wind transducer is a termination and is the reason why it is at the end of the assembly. I can connect it with a separate T at the end and use a termination plug at the end tail. I had it that way initially, but I decided to try it as the tail end and it seems to work fine that way, too. The kit came with 2 termination plugs. Female goes at one end and male at the other.
It seems that the chartplotter and the VHF each have separate power connections directly to the units. They don't get their power from the backbone. Same goes for the Wheel pilot.

 

[chuckwayne]

Great job! I won't try the AT-10 until Escape is on the hard but I'll report after I try to get the heading data to the Ray autopilot (4000+). The chartplotter and vhf draw too much current to be supported by the NMEA2K bus (they should be fused separately, anyway).

 

[HMT2]

Scott, good work! Ain’t it great when a plan comes together?