Is it useless: NMEA2000 In-line terminator - SailNet Community
 
LinkBack Thread Tools
post #1 of 5 Old 01-29-2014 Thread Starter
Member
 
Join Date: Sep 2011
Location: Maryland
Posts: 83
Thanks: 6
Thanked 1 Time in 1 Post
Rep Power: 4
 
Is it useless: NMEA2000 In-line terminator

I just received a bundled Garmin GWS-10 (wind sensor) / GMI-20 (display head), and have a question for folks experienced in NMEA 2000 about the in-line terminator.

In the following diagram an "in-line terminator" is used as a junction between the GWS10 wind sensor and the backbone cable:




What does this do? I buzzed it out with a multimeter and found absolutely no resistance across the pins. It seems to be a direct feed-through for signal and power.

Why can't I just connect the backbone cable directly to the instrument? (The connectors mate just fine.)

The only reason I can think to use the in-line terminator is that it provides some strain relief, but it's a little bulky to mount at the masthead if it's not critical. I have other cables (vhf, anchor light) that will require strain-relief as well, so I figured I'd use 1 clamp to provide strain relief for all the masthead cables.

I'd appreciate insight as to whether or not this thing is really needed.
Reefpoints is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 5 Old 01-29-2014
Senior Member
 
Tim R.'s Avatar
 
Join Date: Mar 2003
Location: Portland, Maine
Posts: 1,543
Thanks: 1
Thanked 27 Times in 26 Posts
Rep Power: 13
 
Re: Is it useless: NMEA2000 In-line terminator

Each end of your network must be terminated to work properly. I would doubt that Garmin or any other nmea2000 manufacturer would specify one if it was not needed.

Exactly how did you test it? Between pins on opposite ends or across pins on the same end?

Tim R.
Out cruising
1997 Caliber 40LRC

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

-----------------------------------------------------

Last edited by Tim R.; 01-29-2014 at 08:18 PM.
Tim R. is offline  
Quote Quick Reply Share with Facebook
post #3 of 5 Old 01-29-2014 Thread Starter
Member
 
Join Date: Sep 2011
Location: Maryland
Posts: 83
Thanks: 6
Thanked 1 Time in 1 Post
Rep Power: 4
 
Re: Is it useless: NMEA2000 In-line terminator

Quote:
Originally Posted by Tim R. View Post
Each end of your network must be terminated to work properly. I would doubt that Garmin or any other nmea2000 manufacturer would specify one if it was not needed.

Exactly how did you test it? Between pins on opposite ends or across pins on the same end?
I tested all 5 pins across opposite ends of the terminator. Unless the resistance is really, really low, (say around 0.1 ohms which is below the sensitivity of my digital multimeter), I'm pretty sure this piece does nothing. I don't have the equipment to check for capacitance, inductance, nor do I believe there are any fuses, internal chips, or circuitry inside this little piece of plastic

I suspect that the true network termination (whatever that really means) occurs at the sensor (GWS10). However, since the NMEA2000 specification states that all networks must be terminated, I suspect this device was generated simply to conform to that language of the specification.

I will set up the network here at home and test it both ways. Unless someone else knows better and chimes in.

Last edited by Reefpoints; 01-29-2014 at 08:54 PM.
Reefpoints is offline  
Quote Quick Reply Share with Facebook
post #4 of 5 Old 01-29-2014
Senior Member
 
Tim R.'s Avatar
 
Join Date: Mar 2003
Location: Portland, Maine
Posts: 1,543
Thanks: 1
Thanked 27 Times in 26 Posts
Rep Power: 13
 
Re: Is it useless: NMEA2000 In-line terminator

There should be a resistance of 60 ohms. Try testing between the pins at the end where the wind sensor connects.

Have you tested an end terminator. Which pins provide the specified resistance?

Tim R.
Out cruising
1997 Caliber 40LRC

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

-----------------------------------------------------
Tim R. is offline  
Quote Quick Reply Share with Facebook
post #5 of 5 Old 01-29-2014 Thread Starter
Member
 
Join Date: Sep 2011
Location: Maryland
Posts: 83
Thanks: 6
Thanked 1 Time in 1 Post
Rep Power: 4
 
Re: Is it useless: NMEA2000 In-line terminator

Quote:
Originally Posted by Tim R. View Post
There should be a resistance of 60 ohms. Try testing between the pins at the end where the wind sensor connects.

Have you tested an end terminator. Which pins provide the specified resistance?
Thank you! You pointed me in the right direction.

Across the network connections pin 4 (data hi) and pin 5 (data lo) in the diagram below there is a resistance of approx 120 ohms in both the end terminator and the in-line terminal.



Now that I can see that it's doing something, it'll get installed. What's one more hole drilled into my mast anyway..
Reefpoints is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
My Manual Bilge Pump is Useless FirstCandC Gear & Maintenance 19 11-06-2013 01:28 PM
Wheel with 1' square shaft; useless? McMikeJr Gear & Maintenance 10 11-30-2011 12:19 AM
NMEA2000 speed sensor MarkSF Gear & Maintenance 2 11-07-2011 10:58 PM
NMEA2000 GPS Receiver question MtHopeBay Gear & Maintenance 7 10-08-2009 10:40 PM
Shorter Single Line Reef Line dnseal Gear & Maintenance 6 11-26-2006 05:58 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome